I'm back to mountain biking after a 25 year absence. A lot has changed... Agree with above, check out bikes in a bike shop if you can. My GF and I had to wait for 2 hours to get into ours on Saturday, but she came out with a new bike so it's all good!

I'm shopping for a new one myself, as all the bikes I'm used to are now labeled "vintage," which makes me a little sad...haha.

Guessing you'll want something for medium to light trail riding? So maybe you won't require rear suspension?