The TTR/AE box is a very good one. The OFNA stailess steel box is very similar, but is slightly larger and will accept a sealed lead/acid battery. Will also accept stick packs.
Integy also has a nice box with the same sort of drive system, for less money.
Things to look for in a box are, sturdy alignment pegs, strong drive system. I like the stick pack power option. It makes for a lightweight box that can be recharged quickly.
Best way to set up alignment pegs is, remove engine so you can sight directly through the slot in chassis. Keep adjusting pegs until the wheel comes up as far as possible through the chassis when pushed down.
I have sold hundreds of starter boxes over the years, and many times people have come back asking for a more powerful box. Stating that this one is not strong enough to start my engine! In EVERY case the problem was mis-alignment of pegs, allowing the wheel to graze the edge of the chassis slot!
I tell them I do not have a box powerfull enough to start their chassis(I love being a smart-ass)!