Hero TAG who hasnt shown down a hand, some steals pf cbets around 75% knows when not to be aggro etc, I think villain doesnt want to get involved with me since there are big fish at the table

Villain winning internet player but with leaks eg. calls down too light postflop, has flatcalled a raise pf a couple of times and folded to my 3bet, also raised twice folded to my 3bet. I think he does think in ranges and calculates math, he knows that I do and if he's good enough, knows that I think of his range and what range I rep to him.

Effective stacks 200bbs vs villain, others 100bb deep

Hand in question:

PF Villain straddles, donk flatcalls in MP, good player flats OTB, Hero in SB w/ AJ raises to $110, villain thinks for 10secs & calls, others fold.

FLOP ($270) 986

Hero takes 10secs cutting out chips, then bets $200

Would you play any street different & why

People defend their straddles pretty light usually, and since you mention that he calls down too light usually I'd be check/folding this flop. Since he understands your range, he know to weight it towards big pairs or overcards, both of which this board sucks for.

eh the fact that he defends light is all the more reason to cbet, you can bet way less though like 120, it will have the exact same effect

if villain calls down light, checking might be optimal. You might still be ahead with AJ, and you're putting yourself in a situation where you're giving action if he has you beat but you're making him only fold hands that you're ahead on. Against light callers, it's usually not optimal to bet in this spot with ace high.
What is the villain's bluffing frequency in position if checked to?
Depending on that information, you might even consider floating OOP in this situation.

cbet is too big. If I did decide to cbet here, I would be barreling most turns and rivers.

Average, but he hasn't been running bluffs against me, has been somewhat consciously trying to stay out of my way.

I had been conscious of sizing my cbet according to board texture because I think he would've taken note of how I cbet smaller on paired flop, 2/3 on dry K83rb type boards and 3/4 on wet boards and c/folded wet flops vs 2 opponents twice in the past.

How likely do you think it is that he has noticed your sizing compared to board textures?