I've never felt any for myself, so I can only really speak from what I've seen in videos and photos, and why I like them there.
My first reason is their overall look. While I'm not big into the whole sort of basketball look (If they can't bounce to some extent, or are basically impossible to squeeze, it's a turn off to me), the look that boobs can have where they're still able to bounce around, and are still able to be squeezed to some extent, is really hot to me, since there's a sort of roundness to it that I personally like more, vs natural breasts.
Secondly is the sort of idea of them. The fact a woman would want to get them at all just turns me on, in a weird way? Granted, some women will want implants for non sexual reasons, but I can see some women who get them for sexual reasons, and the idea of a girl modifying their body for the enjoyment of others, is really hot to me.
Thirdly is how they move around in general. Something about the way they look when they're in motion has always appealed to me. They're technically more limited, and one could perhaps say it looks odd, but to me, that sort of way they can move is really hot, to me.
Fourthly has to do with the sort of feel of them. Granted, I can't judge the feel for certain at this time, but with a real breast, there's only so much there to squeeze. With a fake breast, since there's an implant in there, I feel there's more for one to squeeze down on, which I like, alongside them being more firm, so you can be more rough with them.
Lastly has to do with rippling. While it's generally something that's looked down upon, and seen as undesirable, I feel like rippling where the edges of the implant start to show around the breast, is really hot. Implants that ripple are generally also sorta bouncy and squishy, ive noticed, so that helps, too. Plus, I like the idea of feeling the implant like that. The idea of tit-fucking a pair of rippling tits oddly turns me on.
That got a bit lengthy, ill admit, but those are my personal reasons for enjoying implants as much as I do. I still do see value and appeal for those without breast implants, but I have to admit, I largely prefer breast implants, at this time, and don't see that changing.