Lots of good suggestions here, but as always there really is no "best" because we all have different tastes, needs and budgets.
I play fretless around 95% of the time, and I have owned a lot of very nice examples over the years such as a factory fretless 71P, Veillette Archtop, Status S2, Wal, Ken Smith and an ACG. But, the one that speaks to me the most is without doubt the one I own now - the Franz Sirius. Not cheap mind