Playing devils advocate here slightly, the C152 has one of the best safety records of any light aeroplane - it is virtually impossible to kill yourself in it. Given it is so forgiving, does that really make it the best training aeroplane?
Or would be be better training people in something a little less straightforward? - such as a PA38 for example which is underpowered, drops a wing entertainingly at the stall, and handles like it's out of forward CG limits.
G