About your class list:
1. Druids are great in groups up until higher levels until clerics outshine the other healers. You will very much be able to both group and solo as one.
2. Well-played necromancers contribute a lot to groups! The ones you saw just sending in their pets were bad/azy group mates
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Also: Shaman, Enchanter, and Magician can all solo and are desirable in groups too
[You must be logged in to view images. Log in or Register.]. Shaman in particular sounds like a good choice for you, with powerful buffs and good solo-ability. Ultimately, there are a lot of choices that meet your requirements, and this is really going to come down to you playing what sounds fun to you.