I've been with many well hung men over the years. So far, I have yet to find a guy who was too big.
As for the thickest cock, it belongs to a fuck buddy who has been coming over for about 8 years. His cock is about 7 inches long, and it is the thickest cock I have ever played with. When he first started coming over, he just wanted to be sucked off. Turns out most guys cannot suck his dick properly. It took me a few attempts, but I can go all the way down on him, having his pubic hair and ballsac brush up against my lips. Now, when he comes over, he loves to fuck my face. I have a bench that I lay on my back and let my head hang over. He will come up and grab my throat as he fucks my face with his mouth. He loves being in control. He will fuck my face for a while before he has to stop. He will then sit on the bench and I will crawl up between his legs and suck him off this way while I also jack his cock and pull on his balls. This is the way he can finally cum. While he is fucking my mouth, he is in control of the pace, and while his cock is rubbing my teeth, every once in a while, he will really get into it and change the angle enough that top of me teeth will catch the skin on his dick. It is a painful process sometimes. I never try to hurt him, but his cock is constantly rubbing against my teeth.
Very recently, he has become an anal top. I have begged him for years to fuck me, but he was only into getting sucked. But a few years ago, he was invited to join two other guys for a 3some. The other 2 guys were very much into anal, so he came to me to learn how to fuck. We worked on him learning to open up a bottom before he fucks it with his monster thick dick. How to use enough lube, how to never just rip open a guys hole and how to be gentle and careful while still being the rough top he likes to be. So now when he comes over, he will fuck the hell out of my ass before I suck his dick to get him off. He is one of my favorite tops!
As for length, I have yet to find a guy who was too long. One of my dildos is about 24" long and I can take all of it but the last inch. And that is only because it has a suction cup I mount to the shower wall and then fuck myself with it. My butt cheeks block the last inch from going in when they hit the shower wall.