Mountain bike for an old guy

[Bluside]

I'm 63 and thinking of getting a new mountain bike. I live near a great state park here in Florida with great trails int the woods. My 16 yr. old Trek MTB was converted years ago with slicks and more of a road set of cogs in the rear. It hasn't seen dirt in a long time.

I know things have changed drastically in the past years with regard to frames, brakes and tire sizes.

Any advise on brands and things to look for before I hit my local bike shops would be appreciated.