The Nexstar is a fine trainer but I have to go with jetmech05 on this one. The Sig LT40 is by far the nicest, most gentile trainer I have ever used.
I acquired one myself last summer and even with the LA-40 it flies better than any Hobbico trainer we have. I tried the same plane with a .46FX and it was even better, but not necessary.

I'd bet a student would solo sooner with an LT40 that with the Nexstar with or without all it's bells and whistles.