Originally Posted by Kordanor
Mechanics and then Setting. And then the price must be reasonable for the expected playtime.

The story is not anything I would be able to judge before buying as I wont read into it.

Studio can play a role, but usually it's the other way around. Spiderweb is a good example. I buy spiderweb games because I like the type of games mechanically (and the story, in this case it might play a bit of a role). But if they made an action RPG, I probably wouldn't buy it. So the studio usually just reflects some consistency of other qualities.

About Replayability of Press or what others say I don't care at all (unless the feedback is super bad / game is reported to be bugged or similar).

I was about to write something very similar. Mechanics>Setting>Perspective>Story>etc

Mechanics first and foremost, typically I'll buy anything with party creation and traditional dungeon crawling.

Yeah, as so many have said 'all of the above'.

And while it sounds like a cop-out, when I look at the RPGs I love most they include:
- Fantasy
- Sci-Fi
- Post-Apoc
- First / third person
- Isometric
- Single player
- Party-based
- Story driven
- Action-centric
- Turn-based
- RtwP
- Real time
- Open world
- Map-based
- Highly replayable
- Linear narrative (VtM: Redeption for example)

… and on and on and on