I was in this situation a few weeks ago, and I was looking at basically the same choices. Obviously, Jet is the most expensive, but the cost difference probably doesn't matter much over the period of time that you hope to use the lathe.
In my case, the deciding factor was the bed length - not the specified spindle length, but rather the physical length from one end to the other. I have a relatively small shop, and I have a bench that was built specifically to accommodate a (smaller) lathe. I don't have room for a larger bench, and frankly, I didn't want to build a new one. So I wanted something that I could use with my existing bench. and that ruled out the Jet for me.
The Delta was a very good lathe, but I was also concerned about its future. The fact that the company doesn't seem to have a renewal parts solution was very troubling because it implies that there is no long-term strategy.
There have been some reports of QC issues with Nova, but there also have been stories of how Nova USA has stepped in to help purchasers resolve those problems. All manufacturers have QC problems - the difference is how they are handled, and Nova seems to have a very good reputation in that regard.
But for me, the key factor was horsepower. My former lathe was the ShopFox 1704 - I had a lot of fun with that lathe, but it was really frustrating to try to drill holes with a 1/3HP motor. Drilling end grain with forstner bits was essentially impossible. For drilling you need torque, and it is unavoidable that you will lose torque at the low end of the speed range. So one of my 'wants' was to get as much horsepower as possible.
So I chose the 12" Turncrafter, and so far I have been very happy with that decision.
