Daily and season-long are both great. I don't think it needs to be a competition (for some random reason it reminds me of
this video where Win Butler's egging on his wife, saying everyone in the early 90s had to pick either Pearl Jam or Nirvana, and finally she just says she liked both and he's like, "Yeah, me too.") It seems like for some people they need to pick one format and defend it against the other.
¿Porqué no los dos?
I've found daily fantasy football to be the perfect complement to my season-long leagues with friends. With daily I can go heavy one week if I have a good feeling about matchups or just want some extra riding on the games, and I can take entire weeks off if I just have other stuff going on. In season-long you're kind of stuck with the guys you have, and if they get hurt or just put up a stinker, you never really had a choice (if Aaron Rodgers was your QB in your season-long league, you probably can't really swap him out in week 15 even if you correctly suspect he has a bad matchup). Yes, you're also susceptible to bad luck in daily as well, but at least you have more of an active choice every week.
It also lets you hedge your season-long outcomes. In the championship game next week in your season-long league? Roll out some daily lineups with the players on your opponent's team. If his team blows up and beats you, then you win some money on the daily side to make up for it. Can really take the sting out of losing a close final or something, I've done it a few times and it really leads to a more enjoyable Sunday imo, since I'm not so hellbent on this guy doing great or that guy doing terribly. When you start putting out multiple, diversified daily lineups you can pick exactly the players you want to root for, and can really just enjoy watching football again.
I've been in two local leagues with friends for 10+ years each, and I hope to continue playing in them for decades more. There's something great about that. I used to supplement that with additional season-long leagues but that just became a chore. The combo of a couple season-long leagues plus some daily action every week is just the right balance I think.