The higher the level of the teams in your competition, the more money you get from each match (Although at the higher levels, I think it's only a small difference, not like at the lower levels)

Also most of the high level teams usually aren't managed very well (Otherwise they'd have a higher player quality). The most dangerous teams are often the ones which are the same level, or 1 level above you (Or any which are 1 level below you). As these are usually managed by very active managers.