Well I would suggest an Alchemist.
1. Utility- Extracts for loads of utility effects. Respectable skill points as well, although admittedly not approaching the bard or rogue levels. You could always dip a level into something rogue-ey for a bunch of knowledge skills. You can use Cognitogens to raise the mental attribute du jour as needed for the particular knowledge or social skill you need. You make your extracts at the beginning of the day typically, but if you leave a slot or two free and you have an in-game hour or so of downtime you can make whatever you need to meet a challenge that raises its head, as you come to it.
2. Buffing- with the right discoveries you can use your extracts on other people. You can also self-buff amazingly well with discoveries and feats such as Eternal Potion, Diluted Extract, etc.
3. Crowd Control (not familiar with Arm/Anvil games theory but with dicoveries such as Stinking Bomb (nauseate enemies), Dispelling Bomb, Force Bomb (knockdown effect, harms incorporeals, etc.)
4. D8 hit dice! Buff and damage (at least in terms of versatility and multi-target effect) like a caster, survive like a rogue, especially if you load up Con and Dex, and then use Dex mutagen in combat.
5. While talking about damage, you start with basic Fire damage for your bombs, but you have discoveries available for Cold, Acid, Force, and even Good/Evil "bane" damage eventually.
6. Wanna melee? Use Str mutagen and use some of the mutagen discoveries like Feral Mutagen and go toe to toe like Mr. Hyde.
7. Wanna hang back and lob bombs? Point Blank Shot and Precise Shot feats and Precision Bombs discovery let you lob into melee and call which squares you want to exclude from splash damage, without taking terrible penalties.
8. Throw Anything feat for free! This one is fun. Basically proficient with any splash weapon, not just bombs, and any improvised thrown weapon. You might surprise yourself the things you realize you can throw, especially if you get creative with combat mutagens and extracts like Enlarge Person, Fly, etc.
9. You can use discoveries to increase your survivability. Effective poison immunity comes as you level, the Preserve Organs ability protects you from sneak attacks and the like.
10. Capstone discoveries are really neat. Philosopher's stone can be used to transmute stuff or to give you a True Resurrection elixir once a month. (If you can afford the cost, but at that level shouldn't be an issue.)
11. Lots of flavor and fun RP potential. I admit I was skeptical at first of the class's place in fantasy setting, but there are many ways to flavor the class. True mad scientist, wide-eyed natural philosopher, lab experiment gone wrong, reluctant academic, Batman-style "I've got just the thing for this!-gadgeteer.
12. Action economy. Can do things regarding extracts, bombs, and potions as shorter action types than normal.
I have fun with my swiss army gnome. I feel like I will always be useful no matter what comes up. I'm a newb though so take whatever I say with a bushel of salt.
-Fizz