We use a combination of AIOs (mostly for when we're going out, because I like showing off the cute designs), prefolds/wraps, and Fuzzi Bunz.
The wrap covers we use are Imse Vimse Bumpys, and I will tell you that I have tried just about every wrap cover on the market -- Bumkins, Bummi SWWs, Pro-raps, Litewraps, etc., and the Imse Vimses are my all-time favorite. The Velcro seems a little softer than other brands, and I like the big wide Velcro band in front. They are also very soft and breathable, as opposed to the vinyl/plastic feel of some other covers. So that's my recommendation.
Also, you don't have to use pins with wrap covers. Just lay the prefold in the cover and Velcro it on, and it will stay in place. I know some people like to use pins or Snappis for extra security, but I never felt the need to.
I don't remember anymore where I got my Imse Vimses from! Although these days I try to do most of my diaper purchasing either on the TP here at MDC, or at diaperswappers.
I did buy some of my supplies from Green Mountain Diapers, back with my first baby.