What's wrong with the otterbox defender on the galaxy phones? Even with a curve those cases protect it all..
The sides don't extend higher than the curved edges. If I drop it face down, the screen is finished.
This might sound like heresy to you, but I suggest you try an iPhone.
I was as anti Apple cult as it gets (and still am) before I switched to the iPhone (though it's not my primary phone now since I switched to the LG Exalt LTE flip phone). I was never a person for cases, but when my iPhone screen broke twice (second time was covered by AMEX protection which was used to pay for first replacement) I put it in a SPECK case which doesn't add much bulk and give very good protection (IINM the iPhone X has a much stronger screen, and it isn't curved). I have a 6 plus which I use on wifi for all smartphone type activities that one still needs nowadays.
I've had an iPhone in the past, and currently have an iPad. I can definitively say that for what I do, an iPhone is useless. I need complete file management control, support for external discs and devices, and a whole bunch of other features that Apple thinks we are too stupid to use.
From your criteria Id go with the One Plus 5T. Will also save you some money in the long run.
The screen on the 5 is an issue for me, it's half the resolution of the other options. Plus the fact that I need to pay upfront bothers me.
I'm leaning more towards the Note 8 now, plus the best glass screen protection out there (still researching those). The phone itself definitely meets all the criteria I'm looking for, plus I may be able to take advantage of T-Mobile's ongoing BOGO deal which is quite nice.
I really wish there was an S8 Active in the larger size...