Generic Classes and homebrewing

[Maquise]

Let me set some background first:

I'm in the first thoughts of homebrewing up a system based on 3.5/PF, a d20 system. It started as combining a bunch of variants, then I started thinking up some house rules. (Basically, it'd be 3.PF with a bunch of variants/houserules, different enough to be considered a new system)

One of the things I would like to add is generic classes that allow my players freedom to build their characters however they please. However, upon looking at the UA generic variant, I didn't think it was what I wanted.

I have a couple of ideas. The simplest one is to make the different classes prestige classes (Examples: barbarian prc, bard prc, etc.) What I'd like to get to eventually is having the players pick and choose their "Class features" so that every character can have different builds.

[TooManySecrets]

At one point, I was experimenting with allowing people to purchase abilities for XP. XP was used to buy saves, BAB, feats, skills, and class features. You could buy class features at a cost that was basically Some Number * The Level Of The Class Feature.

Part of the problem was degenerate builds where people would put all their XP into one thing, like buying a bunch of feats. I think a way of getting around that problem is to make it so that only class features are bought, while HD and saves are based off of total XP. Still don't know what to do about BAB and different amount of skills, though.