I do about 4-5 one-year leagues every year, free - Yahoo. Good groups of forum members usually: RHRS is my fave, but the DobberPRO league is also challenging.
I have another I do with some less keen guys, just to ensure I stack up well against moderate-fantasy hockey guys (I should be beating these guys yearly).
I don't like big money leagues.
Those with trading end up being "buddy trade" leagues where when a team is out of it they sort of "gift" some players over to somebody and make up some excuse that it benefits both teams... ha - when one team has no chance.
A good, 1-year big money league has to be NO-TRADING.
For those reasons, I still dig the mass-entry box pool formats - still haven't placed in the top 1% of any big entry pool... one of these days.