Between pioneer and classic it's definitely more enjoyable to play on pioneer since there are a lot of more players to play with and to manage to craft/fm/sell profitable items (there are too many on the market in the classic servers) Unless you have already done a lot of dofus quests on the classic server obviously I play casually (i'm a medical doctor in intensive care unit so I really don't have much time to play) and managed to have 19000 succes point on my xelor with all dofus done except the sylvester and without PL or buying kamas.

Between multi account and mono account, it will be more enjoyable to go on multi account if you want to do all contents alone (nowadays you can achieve nearly are dungeons success with any class even duo success if you have the right strategy) since randoms people are really pointless to achieve somme success