I have been doing leagues for 15yrs. The only way to go is to go with a $$$ leagues that has no Transaction cost and has a 1 time fee. Why u ask?
1. I have found that most of the owners in the league stay more involved when they put the green down to play.
2. The owners are usually trying harder to win. They keep involved till the playoffs are out of reach.(1yr Leagues).
3. Even in Keeper Leagues, you can always trade for picks at the end of the year and build up your 1st/2nd round picks for the following draft.
4. You don't want to get tied up in aleague where you pay $200 for a team, and then $5.00 per transaction. That would suck.
Go for a moderate $50-$200 league that other people do and heard of(ex. Kffl, Fantasysportsguys.com, CBS, TPFS,)
Hope this helps