The Defenders vs The Justice League.

Silver Surfer
Dr Strange
Hulk
Namor

Vs

Superman
Hal Jordan
Martian Manhunter
Wonder Woman

No prep or BFR
I'm character

Namor is a major weak link even though I think he can give anyone on the opposing team a run for their money. With that said, team 1 still pulls the majority.

Team 2 wins.

Team 1 pulls through in the end after a great battle

namor is a weak link, but team 1 does have magic and doesn't have MMH. I say team 1

Team 1 gets the win I believe

Defenders

Team one has a weird team. Namor? Pretty Sure everyone in Team 2 can beat him without much challenge. Hulk can't fly? So t2 can either avoid him till they beat down SS or Dr. Strange.

I say T2 wins because they have the lasso, telepathy, and just as much power as t1 without the weak links.

Defenders.

Surfer can easily keep any two members of the JL occupied whilst the others wipe the rest of the JL out.

JLA.

The Defenders take this.

The Non team has defeated far more Skyfather level threats dealt with threats to the likes of Eternity, faced beings of immense power in their own dimensions or places of Power. The JLA team listed are mostly just powered bricks with a GL. Stange should be able to take MMH and Supes Alone ( let's not forget that when he was a Defender, he was Classic Strange) Hulk and Namor together can deal with either of the other two until SS finishes of the fourth ( which honestly shouldn't take long with Cosmic knowledge and his VAST array of powers.

Let's also not forget that in SS and Strange the defenders have TWO characters capable of time manipulation

Defenders with mild effort.