I lived and died in ASCII Express for many years in the mid-to-late 80's. It had a steep learning curve but was quite powerful, IIRC. (Once upon a time, I had the patience to sit and read manuals.) But now I use ProTERM, since I doubt I could remember how to use AE if I tried.
Also, I don't know if AE ever emulated the ubiquitous VT-100. I know that whatever version I had didn't, and it was a major issue because many dialup services required it for any kind of screen formatting. What I remember being so important about ProTERM was that it could emulate VT-100, though I never actually used ProTERM before eventually switching to a Mac.
I also used a plethora of Novation Apple-Cat specific programs. Com-Ware, Catsend, Cat-Fur, and MegaTerm (a hi-res term program!) are what I remember.