I use Ocean and Earth Premium 8', ankle, for 8' SUP. I had an FCS one before and the Velcro cuff failed. Using an arborist throw rope line for leash string, think it's similar to the Dyneema folks use, the strings before kept wearing out quickly
Ocean and Earth Premium (the ONE) + 2 dyneema cords (main 3mm + a 2mm a bit longer as a safety, + ends melted into the knot with a lighter). I remove (cut) their built-in cord that can fail. 7' for boards up to 7'8" / 7'10"
I had no problem with the Creature of Leisure either, but the O&E seems to me stronger by design. Had various failures with Da Kine, Channel Island (the hexagonal one), FCS...
And of course, I blunt the trailing edge of fins with a Donaldson trailing edge (half-round it)
I've been loving the starboard 9mm 8ft or 10ft ones. About as thick as any I've seen in the market and priced really well. They were on sale at my local today so I got another 2x just for safe keeping!
I had the Starboard thick one. The first time I took it into sizeable waves it got cut straight through resulting in a long swim back. I had the O&E premium one mentioned above last a lot of sessions. It took quite a lot of cuts thanks to the bit of steel, but snapped in December. Now I am trying an FCS leash
I use a waist leash - "home made" with either a 5/16" or an 8mm thick cord, with two leash loops.
I have two other waist leashes from vendors - a LEASHLOK HAWAII which is OK and a Crow Haley, which I think was better but which I lost. Still, I like my home made one the best - that is the one I've been using for a few years now.
When I go back to an ankle leash, whoa...too much pull on my knee.
I think I need that thickness of the cord or more for the volume and weight of my SUPs.
Ocean and Erath one and premium 8'' or 9'', never broke one... Some other brands are good also but call it superstition i use only O&E. I believe the secret is more to change them on regular basis even if visually in good shape. I use them 6 months max for big/medium waves and after that for flat or small waves.
As an old bugger, I endorse most of the comments.O&E and Creatures are both good. read carefully the specs and go for a leash that is more than fit for purpose.in other words a big wave leash that's got enough length. Keep a close eye on the attaching cord which wears with time and can be the weakest link.