This seems like a personal choice more than a backpacking thing. But anyway…
I've always worn glasses. I like my glasses. They look cool. I've tried contacts and they are a pain in the butt to deal with… uncomfotable to wear… and dry out my eyes. What's the point when I can just throw on my glasses and go? I've never had fogging issues except when walking to work in -30C weather when my warm breath can funnel up thru my scarf and behind my glasses… or maybe when our running on a cool foggy night. But 99% of the time for me… fogging has never been as issue.
The only thing I would like to think about is LASIK. Not because I don't like my glasses or I'm self-conscience about wearing them (I'm not)… but because LASIK would serve a real purpose and benefit for me… as an avid swimmer and surfer. I have daily contacts I can use… but when you're getting tossed around by 10 foot waves… they don't tend to stay in very long. So I just paddle out to the lineup and squint. My RX is only 2.75… so I can see well enough… but it would be nice to really be able to see 20/20 when at the pool or out surfing.
As for backpacking… my glasses are fine for backpacking. I've never had any issues. You could always get fitted for some daily lenses… and just try different options. Like… wear the contacts for a trip and see how you like it. Wear your glasses otherwise… etc. It doesn't have to be an either / or.
