I started out with a Moby and loved it SO much when my son was still pretty small; however, I found that as he's gotten heavier, the Moby's gotten less and less comfy for us. He's 17.5 lbs now and I really don't put him in the Moby unless we're planning to sit around the house because while it still starts out great, he's sagged down to my knees in no time.
A friend of mine made us a woven wrap-- just a long piece of woven fabric that she serged the sides of-- and the transition from it to the Moby has been really smooth. We tie it a little bit differently, but after the first or second time, it was as easy as the Moby's been. My son doesn't seem to be able to tell the difference between the Moby and our woven wrap and loves both.
The woven fabric makes a HUGE difference for my (huge

) baby. I feel like it's a lot more supportive and puts less strain on my back, in part due to the fact that he stays in a good position and doesn't sag down to a point that makes me ache.
I don't know much about the different brands of woven wraps, but if you get to the point where your stretchy wrap isn't comfy any more, they're definitely worth trying! If you're not sure you're ready to commit to buying one full price (they're spendy!) and you're not comfortable making your own (almost definitely the cheapest route), you might look for a used one online.