I would say both but maybe start with RE7! I'm a huge fan of the Resident Evil series and while I enjoyed The Evil Within, I was also massively disappointed with it. It's made by the mastermind of the RE universe Shinji Mikami. He reused concepts from RE4, but the game didn't play nearly as well as it and was hardly memorable. The story was quite interesting but had some inconsistencies and requires you to get the DLC to understand one of the main characters. I would still recommend it because from what we've seen of "The Evil Within 2" it's going to be a huge upgrade to the original and it's looking like it'll be an amazing game and probably touching more what Mikami envisioned for the first game. After he left Capcom he had a much smaller team to make TEW with Bethesda publishing. The sequel will for sure have a bigger budget.
As for Resident Evil 7 it's pretty amazing. As a huge fan of the series it does capture the atmosphere but it's also very different. I would highly recommend it because it's much more survival horror based than say "The Evil Within" which is more action survival horror like RE4, but with much less scares (nothing comes close to the Regenerators). Also if you haven't played Resident Evil Revelations 2 yet then that's also a very good one to play as well.
