I don’t use lure clips very often with the exception of fishing metal jigs. When I do, I prefer the egg-type snap seen here in the Daiwa D-Snap and the Decoy Round Snap. I’ve used the Daiwa 8-snaps but I seem to remember losing a metal jig to one once. Size-wise, for proper LRF (sub-7g) you’re probably looking for a size 0 or 00. Keep an eye on the rated strength, but with LRF it is unlikely that you’ll find a metal clip that will give in before your leader line.
As with every tackle item, keep the balance between the clip and chosen lure. Key features of a good LRF lure clip are; light in weight, snagless-design and ease of use.