Disclaimer: The way that my ranking systems are set up is based specifically off of my personal opinion and their utility from a usage perspective in a traditional campaign setting. I view a traditional campaign as being one part roleplaying, two parts adventure and two parts combat. While your ability to roleplay based upon a particular selection will be taken into consideration, I always find that in DnD you can justify roleplaying specific ways despite your subclass. Some people may call that power gaming, but the point of DnD is to be challenged, have fun and stay alive despite the odds. If you die because you want to be cute and gimp yourself, you just failed on two of those. These ranks are also heavily weighted to abilities that are granted prior to level 15 as the vast majority of campaigns end before you reach that point.
You don't have to shamelessly and uncomfortably flirt with the DM as a bard, but your DM and party will likely be confused when you don't. Bards are the jack of all trades and master of many characters. The only other class that can arguably compete with their utility outside of combat is a rogue, and it is not a close competition. Bard spells are geared toward this wide ranging functionality as well. Don't expect to be the heaviest hitter in your party, but if you play your bard correctly you can still very easily change the entire results of a combat encounter. Also, you are hands down, without a question, the party face. If you are not willing to act like it, do not play this class.
Your bardic inspiration allows you to help your party members with their saving throws, attacks and skills checks as well. Expect to be everyone's best friend. The base class is amazing and a few of the subclasses (Colleges) make you even more powerful. Some are a bit lackluster, but will not make you underpowered by any stretch of the imagination.
6: College of Glamour
Pick this if you like the glam and the glitz but don't want any value added.
This college imbues you with fey magic but has always been a bit lackluster in my opinion. The temporary hit points that you get from Mantle of Inspiration is not world shaking and the wondrous appearance, while useful, is a bit superfluous on a character that can already alter other's perceptions with their wit and charm. Enthralling Performance has extremely limited utility and in my opinion is a complete waste.
Mantle of Majesty allows you to cast Command as a bonus action without expending a spell slot. While this is very interesting and potentially powerful from a crowd control perspective, I would not classify it as anything to write home about.
5: College of Whispers
Play this if you want to be a spellcasting rogue, or your campaign is roleplay heavy
You are a bard but you're also kind of a rogue. You are a wolf in sheep's clothing, but this leads to a ton of very interesting roleplaying opportunities. Beyond the roleplay, though, this college is disappointing. The only non-roleplay related perk that you get is Psychic Blades, which is actually quite deadly. You have the ability to expend a use of Bardic Inspiration to deal 2d6 (increases up to 8d6 eventually) damage when you hit an enemy. This is psychic damage, so is very unlikely to be resisted.
You gain the ability to sow paranoia and discord into an NPC or character after talking to them for over a minute, but this has zero utility in combat. You also gain the ability to successfully take on a dead person's persona and likeness, but this lasts only one hour. All in all, this is a very fascinating subclass if you are in a roleplaying heavy campaign. If you are in anything else, hard pass.
4: College of Valor
Play this if you want to be a fantastic support character that your party loves.
This subclass is very interesting and I have always gone back and forth on how truly powerful it is, but today we land at "arguably pretty powerful". You start off with additional proficiencies in shields (which is fantastic!), medium armor (great) and marial weapons (not bad). Much like the Swords bard, you get an extra melee attack at level 6.
Combat Inspiration, however, makes you even better at being a support character for your party members. While holding onto their bardic inspiration from you, they can choose to add their bardic inspiration roll to damage or their armor class. This is pretty impressive but not entirely game changing. What is game changing is Battle Magic at level 14 where you get to cast a spell then attack as a bonus action on the same turn. While this is exceptionally powerful, I do not weight skills of this high of a level very heavily due to most campaigns ending before this level. That shield, though, makes a big difference the entire game.
3: College of Eloquence
Play this if you want to wreck shop in roleplay and be wealthy.
With this subclass you just became one of the most influential and misleading characters in the game outside of combat. You can no longer roll lower than a 10 on any attempts to persuade of deceive an enemy. In all likelihood, at level 3, that means your minimal roll for either of those two is 15. Head to a shop and rake in some dough. At this same level you also have the ability to influence enemy's saving throws using your Bardic Inspiration by subtracting it.
Once you hit level 6 you functionally eliminate miscommunication as well with your Universal Speech ability. You can now make any creature understand you, with complete disregard to language. With Unfailing Inspiration, if your party member fails on their check that you have applied your Bardic Inspiration to, they just get to keep that die. Basically a save or try again infinitely. You are an absolute monster outside of combat.
2: College of Swords
Play this if you want to be a damage dealing fighter that can also cast spells.
The college of swords is a mixed bag that attempts to turn you into a melee character, and does so reasonably well. You automatically gain proficiency in medium armor (great) and the scimitar (for what it's worth, which is not much). You also get to choose between two weapon fighting and dueling, either adding an off hand weapon with more damage or more damage every time you hit. This functionally makes you a viable melee combatant already but limits your spell casting abilities. Either you're attacking or you're casting.
Blade Flourish is the shining beacon of this subclass. You can use your bardic inspiration die to add extra damage to an attack plus you get one of three additional benefits. Defensive allows you to add your roll to your AC until your next turn; Slashing allows you to attack another creature within 5 feet of you; Mobile is kind of weird but lets you push people around then follow them. In my limited intellectual capability, beyond very specific scenarios, I don't think Mobile is great in comparison to the other two. In addition to all of this, you get an extra attack at level 6 making you an even more viable melee combatant. At level 14, you basically just get free AC or extra damage every turn which is incredibly powerful, but comes so late in the game that it is not weighted heavily in my mind.
This subclass is in it for the long haul. If you run out of spells, unlike other bards you are a very valuable member of your group still.
1: College of Lore
Play this if you want to be an ultra powerful spell hurling monster, with a smirk.
It is tough to argue that any other college can compete with this one for the top spot. Your only arguable weakness as a bard is your lack of pure damage dealing spells, and this completely mitigates that weakness. Right out the gate, you instantly gain proficiency in an addtional three skills of your choice. Welcome to nearly limitless utility. Your DM will have a love/hate relationship with you. Speaking of which, your Cutting Words at level three allows you to use your Bardic Inspiration to adversely effect the enemy rather than help your friends. You take your inspiration die and subtract the roll from any attack, ability check or damage roll that an enemy makes. Note: This can not be used against saving throws. Note 2: It's still very powerful.
At level 6 you gain immense damage dealing capabilities when you are granted access to any two spells from any spell casting class that you wish. Congratulations, you now have a bard that can cast Fireball and Spirit Guardians if you want pure damage. You have officially eliminated the only arguable weakness of the bard class.