The guy at my hardware store helped me a lot with this..
He says any sturdy type of wood for the "frame" and legs will do. He suggested a nice one that is easy to sand down and stains well so it can be whatever color you want with your decor but an easy-to-do task.
The major thing was that he suggested you use these brackets to hold the legs (you put two woods together on the edges to form a 90 degree angle and the bracket inside) that have this "extra support" on them? I forget what they're called but they aren't flat brackets, they have this large bump in the middle of them.
Also, use the nice wood to build a "frame" and then keep where the tank will fit in hollow but have a rim around the inside of it. Place a thick piece of plywood on this rim. He said that plywood is much more weight resistant compared to most other woods and won't buckle or crack easily. Especially for something like a 10 gallon it will hold it up very easily and nicely.