I have a original Apple Watch sapphire, not a scratch on it. With the brighter OLED on the newer ones I’m sure you will be able to see the watch without any issues outside. If I compare mine to my girlfriends Series 2, hers is much brighter.
The salhire will be more scratch resistan, but can also be a little more brittle being a crystal. I haven’t had any issues myself, if you one to bang your wrist into tress on an outdoor hike then turn the watch around so the Face is on the inside of the wrist between your leg and arm adding protection. If you drop it the sapphire might break before the glass one, but will also scratch more. It’s a trade off really. I just refuse to use after market bands like from amazon, read the reviews and people talk about the $12 band breaking. Not worth breaking the sapphire crystal for a cheap band, or scratching and possibly breaking the glass screen also in my opinion.
I hope this helps.