In my experience there is a small but noticeable difference. As with every women each has their own distinct taste and like you I to have found the same to be true with each man. So the main difference is brought by the new partner. His "flavor" mixed with my wife's makes each creampie a little different. By no means am I an expert on he subject and have only enjoyed my wife's pussy after another man has filled her up about nine times. Thee has been a couple of guys that I sucked off and swallowed their cum as well as eating their cum from the wife's pussy so I agree with 2wheel is their taste is diluted by the wife's own juices.
I would add that I also find the act of sucking cock and feeling another man cum in my mouth is better then the taste. I get off giving him pleasure, being rewarded with his load, and how empowered it makes me feel to give another man an orgasm.