After playing this, I realized there has to be better ways of playing it, Please give me some adice!

I am in the SB with
To my left is a maniac (BB) playing 50% of his hands and rasing 20%, and fairly aggressive postflop.

To his left (UTG) is a guy that has been run over by the maniac
Maniac has everybody covered, and I have a full stack

UTG limps, I complete, BB raise to 3.5, UTG calls, I call.
Pot is 10.5

Flop comes
Bingo, Nut flush!

I check, BB bets 8, UTG calls, I raise to 25, they fold. (they had to call 17 in a pot of 51)

What is a better line??
1) Lead out, hope to get raised, call. And CRAI on a non paired turn
2) Lead out, push turn
3) Check/call flop, check/raise turn, All in on river, if non paired board
4) Check/call flop, lead out turn (Raise all in if raised), Push river

If they have a set they only have 7 out on the turn

How do you play this?

Two callers is a dream. Call the flop, bet the turn if checked to you (unpaired board assumed) around 60% of pot. If aggressive players think they have a shot you'll know. If the turn is bet (and called) you can push or call if you feel like gambling.

Either bet or check call the flop; lead out for 1/3 pot on the turn and take it from there.

You can checkraise a flop like this with the nut flush, but only if it's a multi-way pot and someone who is normally passive bets at it. In that situation you can often put that player on a made flush as well, and you want all the money going in before another flush card can come to spoil your action.

In this situation, with the read that the guy would bet at this with literally anything, a smooth call and then check it to him again on the turn is the way to go. Let him put you on a bare and hang himself with another bet.

I prefer leading into the raiser here the same I would with a set. I would hope he has an A, raises me, and then we can get it all in. A diamond falls on the turn often enough to cause us to lose all our action. If they don't have an A you're not gonna get much more out of them anyways. This goes for both the PFR and the other caller.