Need some help making the switch back to dual monitors

Hello everyone. I built my system fairly recently. It is an i7-7700K at 4.2 GHz, 32Gb RAM, and a GTX 1080 TI.

Right now I have it pushing an acer Predator X34 ultrawide monitor. Despite the fact that i LOVE how immersive the ultrawide is for some gaming, I find that I just cannot get used to not having a dual screen setup. After giving it several months, I have made the decision to go back to a dual monitor setup.

This brings me to my questions. I haven't kept up with hardware releases/reviews lately and I am not sure which types of monitors to go with. Do I go with 4k or 144Hz? Is dual 4k a thing? Which monitors are really nice quality?

Budget is not really a factor (I mean im not crazy but I also dont mind spending extra for really good products) and I would even consider purchasing a second 1080 TI if it would be helpful fo rthe dual screens.

Any guidance is appreciated.