I was playing 21/18/af3.2/3bet4.1 97 hands on this table.

The villain is 24/13/af1.2/3bet5.7 521 hands

I think it's better to 3bet preflop but I decided to flat instead. The reason being he doesn't isolate at all so it was possible for him to have a decent value isolation range.

He is definitely passive as I watched him play.

So I hit 2nd set on turn but FD/SD completes at the same time.

And the river 7c completes some more SD.

Which one do you prefer?

Check/Call, Check/Fold, or Bet/Fold.

$1/$2 No Limit Hold'em Cash, 6 Players

CO: $238.60 (119.3 bb)
BTN: $269.90 (135 bb)
Hero (SB): $302.30 (151.2 bb)
BB: $142.95 (71.5 bb)
UTG: $251.75 (125.9 bb)
MP: $213 (106.5 bb)

Preflop: Hero is SB with Q Q
UTG calls $2, MP folds, CO raises to $9, BTN folds, Hero calls $8, 2 folds

Flop: ($22) T K 6 (2 players)
Hero checks, CO bets $12, Hero calls $12

Turn: ($46) Q (2 players)
Hero checks, CO checks

River: ($46) 7 (2 players)
Hero ???

Oh, and I didn't bet turn because getting raised there would've made me puke on the wall.

he seems to have a marginal showdown hand and since he is passive and is not bluffing river enough times w air, it seems like an easy vbet around 32$.

I think it's a bet also. I'd get value from worse. I'd make him call with straight. I can fold in peace when he raises with flush.

I would bet a little smaller than $34. I think I'd save money that way vs straight. If I check he probably bets his straight in position but a little more than the amount of my value/block/bet. And I assume he is passive so he won't raise with it so I won't have to bet/fold and get to SD.

However, betting $34 definitely crossed my mind for sure.

Don't worry about straights, he has rarely a straight in his range here. He is hardly going to raise that river aswell when he took that line ott. you said that he isos tight, so AJ is the only straight in his range and he most likely bets it OTT. His river range is mostly marginal showdown value, hands such as Kx and Qx or hands he missed with and gave up OTT. So given he is passive, it is an easy bet. I'd bet bigger, because if he is calling half-potish, he is also calling 75% pot. It doesn't matter if you bet 50% pot or 75% pot, you will rep the same range regardless. Thus you get the same hands that call 50% pot to call 75% pot.

All of this.

Pre is good if his iso range is too small or the limper bad enough.
If someone limps, gets isolated and I am in
position I often don't have a value3b-range.(as a default)
Ott c/c
On the river(if he has bet the turn)c/decide

My basic thinking is to bet an amount that gets called by AQ. Easy game.

I was gonna bet 3/4 pot but changed my mind and bet 1/2 pot instead. I felt it would save me money in case if he has straight, get called by worse, and fold when raised.

I mean what hand is gonna give me action if I bet 3/4 pot on this board texture?

$1/$2 No Limit Hold'em Cash, 6 Players

CO: $238.60 (119.3 bb)
BTN: $269.90 (135 bb)
Hero (SB): $302.30 (151.2 bb)
BB: $142.95 (71.5 bb)
UTG: $251.75 (125.9 bb)
MP: $213 (106.5 bb)

Preflop: Hero is SB with Q Q
UTG calls $2, MP folds, CO raises to $9, BTN folds, Hero calls $8, 2 folds

Flop: ($22) T K 6 (2 players)
Hero checks, CO bets $12, Hero calls $12

Turn: ($46) Q (2 players)
Hero checks, CO checks

River: ($46) 7 (2 players)
Hero bets $23, CO calls $23

Results: $92 pot ($3 rake)
Final Board: T K 6 Q 7
CO showed 8 9 and won $89 ($45 net)
Hero mucked Q Q and lost (-$44 net)

extremely results oriented -ev thinking. At the start i had a feeling that he had a straight, since you mentioned worrying about straights in every post and it made no sense, because straights are an extremly narrow in his range. For example if i beat my opponents calling range 80% of the time and lose to it 20% of the time, should i bet smaller to save money or should i bet bigger to gain value.

So what hands are you getting value from when you bet 3/4 pot on this board texture?

some of the marginal showdown value hands he pot controlled turn with. Mostly Kx. i explained my thought process a few posts back, I could be wrong though.

3bet pre, lead turn, lead river.