Our hand

The most visible criterion for the strength of a made hand is it's own ranking amongst poker hands, since a flush is simply stronger than a straight or two pair by definition.

Number of Opponents

It is basically valid that the fewer the opponents remaining, the stronger the hand. So a top pair is a strong hand against a single opponent but it is much weaker against 7, since somebody will often have a better hand on the flop or will overtake us by the time we get to the river. The weakening of a hand due to large numbers of opponents most affects one pair hands; a straight or flush does not suffer as much.