I like my games to be simple, so I can concentrate on the play. I don't like having tables and table of things to look up.
I like games that have a neat core mechanic, and stick with it so that everything runs off one easy to learn rule. I don't like special exemptions.
I want to be able to run or play a game with only my notes or the character sheet in front of me, never needing to dig through the rule book.
I've been playing around with my own d20 hack system for a while now. I'd become very familiar with the Open Game Licence d20 systems through playing D&D 3.x, Pathfinder, d20 Modern, and all the rest - so a d20 hack seemed like the way to go. It's been great, very enjoyable ... but I've been weighed down by a lot of legacy issues from the original system.
OGL d20 comes close to having one core mechanic, but then it produces lots of special cases. The character class system, the feats, the skills - there are far too many special abilities, specified DCs, and so on: too much stuff to look up.
So - I've been thinking about how to get rid of look ups. Using d20 as a base to work from (partly because it's where I'm starting from with my own hack, but also because it's OGL and we can all look at it for reference), I'm going to present alternative methods and examine them to see how they stand up.
At the end of this process - or at least after several iterations of the process - I may have a plan of cuts and adjustments to make that'll turn my d20 hack into a system that really stands up by itself. Or I may just have a set of house rules to bolt onto the rules as written. Either way, I'll be happy.