As stated above, this entirely depends on where you ride and how you ride. Like many, I started riding and racing on a hard tail in the mid 80's, but my full suspension riding first started in 1990. I have gone back and forth several times since and have owned fleets of both styles of bikes. For me, I'll only ride hard tails here on out, but I know how I like to ride and where I like to ride. My path has taken me to 29er hard tails and I've never been happier.
Regarding weight, do keep in mind that weight is only relative to the weight of the bike AND the rider and even then, only within the world of climbing. Climbing speed is the product of weight (bike+rider) vs. watts, so unless you don't have another couple pounds to lose, don't worry about a couple pounds on your bike. And as we all know now, rotational weight myths are now bunk, so as long as your bike is in "normal" weight ranges, that's all you need.
Regarding materials, the best way to spot an uninformed opinion is to look for people who generalize and say things like, "titanium is this and aluminum is that...." Materials are only what you make of them. You can get just about any material to do anything you want it to do. Keep in mind all frame builders are shooting for the same goal - lateral stiffness and vertical compliance. Just read through bike reviews and you hear the same mumbo-jumbo regarding those qualities regardless of the material. So, should you seek a carbon bike with stiffness and compliance, surely you can find it. Same for Scandium, aluminum, steel, ti and even the bamboo bikes I've ridden can be made to feel pretty slick.
Honestly, I'd just be careful soliciting advice on what to get. No one will know what you need more than you. Take a mental inventory of where you ride and how you ride and start there.