Help me choose a GPU please

Hello, been running GW2 quite smoothly in 1440p with my current gpu, but having done lots of wvw i always kept all minimum graphics. Lately i prefer doing open world and instanced content, and also fashion wars, and upping the settings makes the fps suffering.

I got ryzen 5800x3d, 16gb ram and a nvidia 1070... Which i guess is the top priority to replace. Budget is like 300-400 euros (EU).

Thanks for any help, i just want better fps (not necessarily in zerg fights and world bosses which i know is really hard to get big fps, if even possible)