I have three. Two round ones I got from the city and a square one I got from Sams Club. The best one is the big round one that has a lid that catches rain water and lets it drain into the compost. It has better ventilation and, as it isn't tapered and has a wide top, it is easy to stir. It's the biggest also.
The other round one tapers to the top and is difficult to stir. It keeps the rain out so I have to add water.
The square one from Sam's Club doesn't let in water and it doesn't breathe very well. It and the tapered round one are both too small and take the longest to compost material.
During leaf season, the city had a free how to build your own composter class. Basically, they took a section of wire fencing and tied the ends together to form a cylinder, stand it up and fill with leaves. Simple and cheap, but it works. You can also get black garbage bags, fill them, poke some holes in for ventilation and wait.
That's what I do.
I bought a 10-foot length of hardware cloth, 3 feet high, and wrapped it in a circle and tied it together. Fill it with leaves, produce scraps, manure, et cetera. I don't turn it.
Once every spring I unwrap the cylinder, move it to another location, and shovel the unfinished stuff from the top of the old pile into the cylinder and use the finished compost on the bottom, bagging up any extra to use later. If you want more suggestions on composting, go to the gardenweb.com forums. There is an entire forum dedicated just to composting.