Arilyn
Hero
I believe the flavor of any given class has more to do with how you role play the character than the mechanics of the class.
Alchemist - Wizard sub-class with a discount ability to brew potions and consumable items. (like each of the spell schools)
Jester - Bard or Rogue with Performer background.
Artificer - Wizard sub-class that grants crafting abilities - like the Forge Cleric.
Summoner - Wizard with more summoning spells. Sub-class that grants discount to learn summoning spells, feature that extends duration of summons or something.
Witch - Warlock
I think the only tough one is psionics. But, I'm not a fan of Psionics being 'just another magic type/class'. Historically, psionics was a bolt-on system that could manifest in any class. Maybe a Background or Feat.
But if the mechanics of a game doesn't help me create my character concept, it can get frustrating. In classless games, I can usually make whatever I want. In FATE, for example, I can build my character from ground up. In games like DnD, which have classes, I am dependent on pieces that are given to me by the designers, unless I want to do a lot of work designing my own. Therefore, I want that huge Lego box. I can do more with a full alchemist class, and feel more like an alchemist than I would with a wizard sub class that has a few alchemy bits added in, especially since subclasses don't have many entry points. As far as role playing? More options isn't going to dilute my imagination.