I fill that 2 players tables game is more predictable. From your expirience can earn plaing 2 player tables as much as 6 player?
It depends what you enjoy more and/or what you are better at.
However, in my experience, the heads-up field is generally much tougher than 6-max, but rake is usually the same. Therefore I recommend 6-max tables. Besides, they require much less concentration and, depending on the stakes you are playing, you have to worry less about being exploitable.