Theres always tons of opinions about the best second plane, might be a good exercise for you to learn to use the excelent "search" facility provided by The Universe

I always mention the Hanger-9 (sorry AM) Advance-40. Its a low wing with excellent stall charateristics. And most of all, its a tricycle landing gear making it easier to handle on the ground. I'm sure theres others in this catagory.

I didn't start with it and ended up wrecking my second plane, because I had to get a "cool looking" Messerschmitt, but thats another story ...