As you know from other threads, I tried one recently, testing it side-by-side with the Oasis, and the Forma is the one I preferred.

Oasis Battery life: My sample of 1 was significantly worse than any e-ink reader I've owned or tried, including those tried recently (Kobo Clara, Forma, PW4, and Oasis). It did meet Amazon's advertised usage of roughly 21 hours with wifi off and light level set at 10. But in contrast, my Forma lasted longer with wifi enabled than Oasis lasted with wifi disabled. Although, I don't think Oasis battery life is a show-stopper for anyone provided you are expecting what Amazon advertises. It lasts 'long enough' for extended reading sessions.

The Oasis screen is meh, for me, given the price of $279.99 for my 32GB version. I expected a lot better for a nearly $300 device. It's barely bigger than the PW4 screen, and not visually any better as far as I can tell. For me and my wife, the Forma's larger screen, with better lighting options including natural lighting, was much preferable. We could get the Forma screen to display beautifully using the natural lighting in nearly any conditions.

The real deal killer for me was the slippery, cheap feeling aluminum surface on the Oasis. Ugh, I cannot believe they designed it with such poor ergos and expect people to cough up $250 to $300 for it, or worse, cough up an additional $12 to $50 for a case, which also adds at least 4oz to the weight. Once again, the Forma's grippy surface and design with the slightly bent edge, felt more deluxe and usable--comfortable to hold without being slippery--and the Forma came out on top for ergos in my review.

The only things I ended up preferring about the Oasis are the wonderful inclusion of the Oxford English Dictionary, the better value vs say the Forma (a 32GB Oasis was the same cost as an 8GB Forma), and the easy access to Amazon's ecosystem. But given that I can have all of those things on my PW4 for a lot less money, I didn't have any compelling reason to keep my Oasis around. It has been gifted to someone who will use it.

Hope that OP continues to enjoy using the Oasis. Regardless of my reaction, they're still a deluxe reader and I get why a lot of folks like them. But I confess it surprises me whenever anyone who has recently tried both, prefers an Oasis over a Forma.