Similar to your other AJo hand, I would prefer betting the flop for a small size rather than going for the x/c. Boards like this where villain should never have any 2 pair or straight/flush combos are great to barrel. Of course he can have sets but they can always have sets.

As played turn looks good. River vs a complete unknown I probably wouldn't be able to find a fold though I think folding could be acceptable. I'm guessing AJ is on of the best hands you'll show up with here. Without info on villain to say he's value heavy or bluff heavy, I just default to not folding my best hands.

1st of all, your 3bet size is way to small. You will play oop and your sizing should be 3.5-4x his raise. You are giving him very good odds and he will call way to often and AJo is not a great hand to play oop in a 3bet pot.

Other than the fact that I prefer cbetting here over check/calling I think you played the hand well (assuming you folded the river).

Pre flop OOP versus a x3bb open 10-11bb would be my standard raise size.

Not sure why you didn't c bet like in the almost same other hand. Definitely prefer it to check calling.

As played I would actually fold the river. Micro players won't fire three as a bluff here often enough, and many will even put you on AK and check AQ AJ down.

Preflop looks ok.

Not one of the greatest combos on the flop, although we have some of the backdoors. I wouldn't be surprised to find x/f is best play depending on how rest of range is played. Cbetting can be reasonable, although I expect the EV to be marginal. Probably x/c flop has the lowest EV. River pretty straightforward fold as played. I doubt we can ever fold the turn though.