At the end I couldn't wait and I bought the GTX 1660 ti for 316€. Although the Vega 56 was a good option, and the 5700 XT was definitely worth the extra money, I thought NVENC was nice to have for me, since I want to get back to streaming in some months. And the 1660 ti will do just fine until I finish my career and get a good job.
Thanks for the info anyways ^^