Click on this link instead:
https://docs.google.com/document/d/1QuuQqCPPSUVenh4oahDQSZKBDaMCEVNyHhVgByFMk18/edit
The OP has a lot of information but this document is more up to date and includes the new gods we just got from the Godfest.
From this list you ideally want anything in Good Tier and above. The link also includes pros and cons of each God which is important, especially if you aren't going to be spending money on this game.
There's the doc I was thinking of! That was tremendously helpful to me when starting out. You'll likely be fine with anything listed "good" or above there as Kreed said. By the time you actually need S-tier gods for some of the toughest dungeons, you should have hopefully already pulled on a free pull. Heck, it'd be tough but you could probably run even the toughest dungeons with most of those.