Skarty

I don't play alot of 2ks oonline so i might oversee a thing or two but here is my analysis:

River seems like a clear fold. On this board structure, and given he calls you on the flop with 3 ppl behind him, he doesnt have any bluffs in his range and is very likely to check back all of his one pair hands on the river. Donk leading seems to be quite terrible (on this river and this potsize) and i don't know what do you want to accomplish with it. 

The turn is a bit more tricky but let's analyse it.

You said that the opponent likes to see flops so i would assume his range on the turn is sth like that: J10s-AJs, AJo, 33,88,JJ,T9s. 

Board: Jd8h3s7c

Equity Win Tie

45.45% 0.00% { JJ, 88, 33, AJs, KJs, QJs, JTs, T9s, AJo }

54.55% 0.00% { KdKs }

If we look at the combinations of hands we have for J10s-AJs 3*4-1=11 (since we have the k of spades), 9 for AJo, for 33&88&JJ 3*3=9 and 4 for T9s. So we are ahead for now 20/33~60% of the time. However i would assume that on every river he is going to bet only with two pair+ and sometimes with AJ, and therefore (depending on the bet size) would c/f almost every river. If we keep that in mind i would probably prefer to bet on the turn, since we could accomplish multiple things:

1) He raises and we have an easy fold
2)We protect our range a bit since he is likely to fold KJs,QJs and probably J10s. This is good since he is only going to bet those hands on the river if he improves.
3)We can select the turn size. This gives us also some room to decide whether or not we want to b/f river small.
4)He might not bet AJ that often on the river if we bet the turn and therefore have a more straightforward fold on the river if he bets river.
If we c/c turn it makes life a bit harder on the river since we then have to decide whether or not we want to call river on our assumptions on his frequency to bet AJ. If the rivercard is a 9 or higher i would just c/f river if he bets. He could check back on the turn, which would be great but he is probably to do that only with KJ-J10, hands who can catch up. 
Although i think both c/c and b/f is fine on the turn, i would probably b/f turn and then b/f river small on river card <9 and c/f on river card > 9