There's definitely no such thing as a "best all-around trail bike" -- there are way too many variables, which is why there are thousands of different mountain bikes out there in a wide range of prices. (Until recently, most big companies made ten or twenty styles of mountain bikes every year and road bikes were more of an afterthought with two or three models.)
In your case, "what sorts of trails?" is narrowed down a little -- Arizona means you won't be fighting the roots and mud that characterized eastern US trails for years, but that only helps so much. Are your trails mostly dry and sandy and fast? Rocky and technical? Lots of climbs and descents or mostly flat?
Cost is probably the biggest factor -- do you really want or need additional costly features like dual suspension and disk brakes, or would an older hardtail with V-brakes do the job of just getting you out there on the trails to see if you like riding off-road?
At 6' tall, there are TONS of bikes that will fit you, but even that is a matter of fine tuning. If you've got long arms and legs, you might like the longer top tube (and thus the longer cockpit) that Specialized frames used to offer; if you've got average (or shorter) limbs you might like a "normal" frame instead.
I would suggest hitting a few of your local bike shops since they probably know the local trails better than anyone, and seeing what sorts of bikes THEY suggest. If you've got an unlimited budget, you can just buy one of those shiny new bikes -- but since you probably DON'T have an unlimited budget, you can take note of what features (like wheel size) they're recommending and look for a nice used bike. I'm only guessing, but there are probably many more VERY nice used bikes in Arizona than there are here in Ohio -- people who leave their bikes outside here for a couple of snowy or rainy winters usually find a rusty mess in the spring.
If you do like riding off-road, your first mountain bike probably won't be your last. You'll find (or they'll invent) new features that will make your riding better, more fun, and/or more comfortable.
