OneSize diapers are all the rage these days, but for a dependable diaper that fits well and can last through multiple kids, regular pocket diapers are the way to go. We carry several brands at Cloth Diaper Outlet, but there are a couple that we really love that have been in our stash for a long time.
Fuzzi Bunz - Great diaper, dependable, pretty much leak proof, and fits our daughter well. We've used these since the very beginning. She wore a medium from 14 lbs to about 30ish pounds, which took her to about 3 1/2 years. Then we switched to larges for her night diapers. We can easily put two inserts into these and, at 40 lbs, she still has room to grow in the larges.
Knickernappies - Long a favorite in our house, Knickernappies have made up the bulk of our stash for about 3 years. Mediums lasted to about 33 lbs, then we switched to larges for night. We LOVE the 2G version of the Knickernappies diaper. Side-Snaps are our favorite since they are so easy to do up and don't cause any extra bulk in the tummy area. The 2G version is virtually leakproof and has plenty of room for inserts.