Seasonal ranking.

If you play against an opponent with a significantly lower rating, you won't gain much rating points upon winning (if the difference is more than 400 points, you get +1 for a win and -32 for a loss, I think), so farming rating points against weak players isn't the best idea. I don't think that the tournament rating is better than the overall rating (seasonal + tournament). In the group stages of tournaments, you often encounter weak opponents, while in the seasonal ranking, some players specifically look for stronger opponents.