Can't help you with any opinions on the Varycon paper. I have used glossy, RC versions of both Arista II and Arista.EDU Ultra papers. I can't say if the fiber based versions are substantially different. Both papers are pretty good, but the Arista.EDU Ultra suffers a little more from hazy blacks if you view them from just the right angle. This is a pretty common complaint with a lot of RC papers, and something that I rarely if ever see with fiber based papers.
I tested both papers by contact printing a 31 step wedge using the Kodak Polymax filter set with the Arista.EDU Ultra papers and the Ilford multgrade filter set with the Arista II papers. All test strips were developed in Dektol 1+2 for 2 minutes. The Arista.EDU Ultra paper definitely has more range, and is much slower than the Arista II paper, and has a warmer tone. Both papers respond more agressively to selenium toner than Ilford MGIV paper. To give you an idea of how each paper responds to filter changes, see the attached files.