PCnoobmuch :
I am not really sure, i am thinking rx 470/480 depending on the price, probably rx480 b/c pricing so close. I would go with a cheaper GPU if i think 16 gb needed but i think 8 gb will be fine, yes?
I wouldn't even bother with a GPU for Photoshop and Lightroom. The functions they accelerate are relatively minor and aren't used that often (mostly filters). The GPU does (supposedly) accelerate Raw processing in LR, but according to benchmarks the speedup by the GPU is negligible. Video rendering (Adobe Premiere) is where a GPU really helps.
LR is pretty frugal with RAM, so 8GB should be fine. Photoshop is a RAM hog though, and having lots of it will greatly increase your undo buffer. (LR records edit steps in its undo buffer, and recomputes the effect of edits on the image on the fly. So it only needs a few kB for a long history of edits. OTOH, the important part of PS is layers, and those layers will eat RAM like candy.) PS will mostly work in 8GB. But if you work with large photos, a lot of photos simultaneously, or do a lot of editing on each photo, 16GB will be more comfortable.