Hey everyone. I wanted to give a little bit of info here in case it helps anyone else out who wants a protector on their watch. After getting my watch last year I went through tons of different brands of soft (wet-install) screen protectors (did not try any glass ones).
I tried Skinomi, Tech Armor, Best Skins Ever, some generic ones from ebay, even a cool +-shaped one with no corners. All of these protectors did not last more than a month at the extreme before the corners started coming up. (The +-shaped one didn't have that problem of course, but it did pull up when it rubbed on something the first time) Pretty much all of them had it start to happen after just a few days, and very slowly got worse over time.
I happen to try one on amazon that had good reviews and this one has been amazing. The corners went down very easily (just like the others, let it sit for 20-30 before doing the corners) and stayed down. This protector feels like it has a much stronger adhesion to the screen though. Even after weeks of use it looks like when I had just put it on. Corners have not come up at all so far. I even pulled up the top-middle to get a hair out from underneath and after wetting, it has stayed down like I never touched it!
I'm very, very impressed with these so I thought I'd share. I'm going to link the amazon page, but I am not affiliated in any way so don't even start that.
https://www.amazon.com/gp/product/B01G7UJI2M - I have only tried the 42mm so far (but I expect I will buy the 38 for my wife when she's ready to replace her current BSE one)
Here are some pictures (since most really like those), but it's hard to get a good shot of such a thing so I apologize for the smudges and hair!