I love titfucking in all it's forms, but I prefer the girl on her knees, holding her tits and going to town. It's all in the way her eyes look up at the guy..
It really depends on the size. If they're some huge DD's you can really pull off either position. It's nice when they're big enough and you can lie down and have the chick mash them together and do the work..like Brandy Taylor in clip 3
I'd do it hanging from the rafters upside down by my knees if that's the only way I could get it. These days, that ain't often. Ahhh, to be young and full of adventure once again!
I love her on her 4s with her breasts "hanging down."
I also love DD+ cups where the woman can just "throw them up and down" while sitting (neither you or her have to move at all).
But I definitely love the "reverse" position where you're facing her pussy.
I've pumped into a lot of bras and other tops and totally creamed them that way.