Hmm, my first thought is to simply ask the students to each try a different one out and see who finds the best.

I pretty much just use openscad, and while i do have a very good version that runs on android - you need a bluetooth keyboard to go with it otherwise the onscreen keyboard just obscures everything.

But yep, I'd make it a class project - get them to track different packages down and try them out. Person who produces most useful and printable 'thing' wins a prize :-)