XTOL is a newer product but it isn't a newer version of D-76. It's a different product.
I normally use D-76. For Tri-X, Plus-X, Tmax 100, and 400, it works very well. I like the result.
I used to use XTOL. Initially, I had trouble of getting excessive contrast so I had to reduce the dev time by 15% to dial it down.
It seems (meaning I haven't done a scientific comparison test), for push applications and Delta-3200, XTOL appears to work better in producing smoother image. D-76 is also quite a bit more forgiving.... It gets me the result I like - every time.
I've pushed Tmax-400 and Tri-X to 1600 and processed with XTOL with absolutely fine results. I haven't done the same with D-76.
I'd say try both and see which one you like better.... they are both pretty cheap.
Sorry, this is kind of random.