If you're learning, I'd recommend going with whichever is cheaper (probably the Arista.EDU Ultra 100). There's no point in paying a premium price for materials that will end up being ruined because you're still learning how to do it. AFAIK, there are no differences between film brands that will make it harder to learn with one than another, with one possible exception: Quality control on some brands, such as Foma (which makes Arista.EDU Ultra) and Efke is less good than on other brands, such as Ilford and Kodak. This may make it difficult to determine if some problems are the result of your own errors or a defect in the emulsion. Being aware of this fact can help mitigate problems. For the most part, Foma/Arista.EDU Ultra and Efke are just fine, but there have been posts here on APUG about bad batches that have various problems, so keep your eye out for such posts, particularly if you have problems. I'm not sure if there's much to distinguish between Foma and Efke on this score.
I've never used sheet film, just 35mm and medium format. In those sizes, Foma's products seem a little more technologically sophisticated than Efke's (smaller grain size, for instance), but they're more alike in most respects than either is to bigger names. Efke's ISO 25 and 50 products have reduced red sensitivity, which can alter the appearance of some scenes (reds will appear a bit darker on Efke film than on Foma film). I don't think this effect is very dramatic, though.