Travis McGee , Nov 21, 2012; 09:49 a.m.
There is no single answer to that question, but I have a 7D and I use an EF-S 17-55 f/2.8 as my primary lens and I carry an EF 70-200 f/4 L in my bag. That combination works well for me.
By the way,there are rumors of the 7D II coming out early next year. If you can wait, you might find the 7D on sale after that happens.