Reeeeeeeally can't understand what makes you unhappy with Summoner if you like Arcanist. As people have been saying, Summoner is upgraded Arcanist, and no, staying an Arcanist IS NOT an option, you WILL be booted from groups. The only difference right at 30 (aside from the stat boost for Summoner) is... a few cross-classes? Not even particularly good or useful cross-classes? Whereas at level 35 you're going to get Fester as a Summoner and let's just say that Fester alone is better than every non-THM/ARC cross-class combined.

If you liked Arcanist, go Summoner. It IS the continuation of Arcanist, period.

A Scholar is a healer, which is a very different style of play. You may like it, but it's going to be a departure from Arcanist. You'll have to get used to being a healer, not a DPS.