Yes, simple and flat would be my preference. Realistically, though, I could easily go with 'simple' right now... if I didn't try and use any loopholes, it'd be simple. So, I guess I only want simple if it reduces my overall burden ;-)
On the surface, it seems easy, flat tax of, say 15% across the board. Home owners don't receive a benefit over renters. People that max out their 401(k) are no better off (from a tax standpoint) than someone that can't even spell 401(k).
In practice, though, how does that work out. I donated a car to charity last year. It's not altruistic because I'll be able to claim the blue book value on my taxes... not bad! Would charitable giving go down across the board? I'd like to think not, but I'm not so sure.