Another married bi guy here. I agree with MKSub24 and Olderkinkybiguy on many points. I don't know about 'best' but I do know fucking married guys can be quite fun.
I was married when I had my first experience with a man. During our first threesome, the guest popped my cock into his mouth while he was fucking my wife. It felt fine, not wrong, and it definitely did not last long enough. The DP later was pretty good. That event didn't register much, but I was very much into bi porn by then. Two years later we were playing with a couple, when it did register. I knew the hubby was bi. He and I had flirted on messenger. At one point, he and my wife together went down on me. I was shocked, not by what they did, but that he felt better than she did. In fact, better than any oral I had ever received. Then she and I shared him. I liked sucking him and getting reactions. Later that same evening, he fucked me. My first real cock fucking my ass. That registered bigtime. I really liked his cock ramming into my ass, and the feel of his body and his expressions. From that point on I was hooked on sex with men. I discovered, it feels more fun. It feels different. It is usually sex for its own sake, kind of like a fun sport but more, and not necessarily romantic or tender or loving. Friends can have sex on a whim and its cool. Fuckbuddies are great. Less inhibited. Can be more easily spontaneous in interesting places. It happens more easily and can be more frequent. It can be harder and more intense. The interest in sex doesn't seem to drop off as quickly unless there's a really good reason. There's a better chance others can be involved, too, and be safely open about it. Sex with men simply feels good.