i compared them both when i had one of my amp reverb tank fix with an amp tech, can't hear any difference in tone honestly. it was the korean accutronics with the mod, we even comparing them with a real accutronics. sounds very similar, if there is differences definitely its something that my ears can't captures.
I swapped the stock Accutronics tank in my Blues Jr with a MOD (Ruby) tank and noticed a longer decay and overall deeper effect. I also swapped the stock Belton in my AC15C1 with a MOD tank and it was a little less intense.
So in my limited experience, the amount of dwell / length of decay seems to be Belton > MOD > Accutronics. In the BJ I wanted more, in the Vox I wanted less... so which is "better" kind of depends on the amp and your taste, I guess.