Battle/homunculus support alchemist+ plant bottles is great fun, even in parties.
The few I've been 'allowed' to come with, my mammomite tore up pretty hard. On top of it, I was pretty much independent since I could heal right up with a couple white pots if need be, use geographers to heal the party in a bad situation/keep myself going while fighting, or plant lolis up front to tap mobs.
Thing is, takes a lot more work than most classes I've played. If it came down to my absolute favorite, and this is going to sound like blasphemy coming from the sinX main- High Priest.
I love it. Even though parties can get a bit droll, tediously healing/buffing constantly, the build I'm in can utilize every part of my skill tree aside from the battle priest skills.
Can magnus things, turn undead things, support 1,2,3,4,5,6,7,8,9 people besides me, tank things, and pretty much do them all a thousand times better when a serenading class comes along. (<3 bragi & service)
Basillica is pretty damn lulzy too.