The late Lynn McCrosssin aka Pec Panther was one of the best. I can't find an example here on site though.
Crystal Anthony is also quite adept at making her pecs dance and, given how big her implants are, those pecs are moving quite a lot of mass.
Natasha was def a surprise. Sadly she hasn’t posted anything catering to muscle fans in ages
Honestly Anne Dudash might the best at it. Pre-boobjob, it was effortless for her. Back then she could bounce her pecs to the music no matter how fast the beat was. She'd be able to keep up like it was nothing. She could isolate the left or right side without even trying. I think it was an old HB+ clip where she told a story how she'd be at work typing on her computer and be pec bouncing the whole time just for fun. She can still do it great now but it requires more of an effort with the extra added weight.
Which is the best fbb pec bounce video you've ever seen?