At the end of the day they're both good e-readers but for me the larger size Forma was actually the big reason I switched. Portability isn't a factor for me but if it was I'd go for their smaller Libra model. I find the Forma lighting considerably better and more even and the font rendering better as well. I'm also not a big fan of the Oasis cold metallic feel... much prefer the Formo plastic / rubbery feel. I think for most it's a preference thing.