Instead I will focus on three I've been in for years: G4R Madden, True 32 Sim and Fantasy Madden 281. Each has a multi-commish staff for checks and balances and I like the diversity, structure, discipline and leadership they provide. They run year round (since M'13), stay full and advance on time if not early. Some have tried them and found it not to their liking while others revel in them. All good, people have different perceptions of what a credible league is and I'm not here to judge. Let's jump in shall we and get to what makes these 3 stand out for us.
G4R: It's considered the entry point of the 3. It has guidelines in place to keep the hardcore guys challenged and friendly enough to introduce newcomers to franchise play. With live post game conferences by coach G-Love himself what's not to love? Some call it the most sim of the trio but that term is overused in my opinion. No two people will 'ever' agree on what sim is. Its one of the few lgs that has had a female player since 'M25. Over 1/4 of it's original members since day 1 are still here. A cpl members vow this is the 'only' lg for them.
True 32: Rules are a little more loose than G4R and you 'must' be able to take a beating. In fact many have jumped in this league gung-ho only to leave after a brutal initiation by a fellow opponent. It's not lobby by a long shot but you can let your hair down and air it out more. Consider it a cross between G4R and 281. True 32 is one of my personal faves.
Fantasy 281: Some call this the flagship of the 3 and no mercy is shown whatsoever. With limited rules its a notch short of EA's anything goes Madden Tournaments. Picture MUT in franchise mode where teams are full of superstars, some players 99 overall. League has a 'hot seat' where you must win a minimum amount of games each season to stay onboard. It's a refreshing twist and makes you weigh every game heavily. Of course exception to the rule are staff and contributing members who put in countless hours to help keep lg flowing. Get ya weight up fellas, only thing harder than playing in this lg is trying to get in. Members tend to stick around for the long haul.
Note: Article is not a ranking of leagues nor debate forum for what is and what isn't sim. Only an insane person would go down that road. Adjusting rules and sliders does not make a lg sim, neither does having members who are ex football players. They bring a different approach to the game and though insightful is not a be all end all. Its a topic for another day. In short its a video game and meant to be entertaining sim or otherwise. When it ceases to do so no label on the planet will keep you around. Look for other featured lgs in the future.