I would recommend using L1 and right stick depending, with L1 I have mine set goal side but it's about what you find better to use, and try changing right stick to be based off of the player you're using. It makes it much easier for me to find the player I want at least.
I know what you mean about the marking, they deliberately toned that down because of how it was, do you ever use R1 contain to get a player in front of them? It's not the best but it helps contain them till you can switch and make a tackle.
Also do you ever double tap and hold R1? It makes 2 ai players contain possible passing options. It's tricky to get the hang of but quite handy once you get used to it.
Those are the only things I could think of that might help with what you're experiencing