Best converting product on Clickbank?

There isn't necessarily such a thing, because the one that's the best converting for someone else may not necessarily be the best converting one for you at all.

It all depends on how they're pre-sold, and especially on the relationship you build with the list you build.

Conversion rates aren't available, anyway, other than claims from vendors, and the experience of affiliates, if they're willing to divulge what they're promoting and how they're doing with it. So all the information you can get about this exact subject is always going to be either second-hand or unreliable. Or, of course, both.

If it helps at all, out of just over 20 products I've now promoted altogether, my best two converters and highest sellers by far have been and are a couple of products with gravity figures close to 5. One of those two products' vendors also has another product in a totally different niche with a 3-figure gravity (about 120 now, from memory) but he steadily sells far more of the low gravity product, which is also higher priced. I'm not talking about anything unusual or strange here: that actually isn't atypical at all.

Don't imagine that high-gravity products "convert better". Quite often the exact opposite is true, and there are good and valid reasons for that.