The roundlock is really clever- much more limited than a padlock in what it can actually lock, but it works superbly with suitable chains. The pin is completely surrounded by the chain so it’s basically uncuttable. Fantastic value. It’s a little fiddlier to fit, though.
The squire is pretty much a benchmark and has been for ages, but it won’t work with 16mm chains, so you’re basically paying a lot for an excellent padlock that can only be used with a probably inferior chain. Doesn’t make sense to me. You need to go up to the 65 I think to get the larger capacity and that’s bloody expensive.
(can you use their d-lock with the 13mm? It’s a nice bit of kit)
If you can possibly stretch to the 16mm chain, the difference between boltcroppable and not is massive. it’s also much more resistant to grinder attacks, being 50% more metal to cut. You might be able to save money on length- people always tend to wrap a loop of chain around bikes, but you can also secure it at one end, pass it through, and then just loop and lock the end around the bike- I had 3 bikes locked to an anchor with a 1m chain.
(you also get more options with the 16mm chain- I have a couple of cheap Onguard Brute d-locks which fit through the chainlinks, so I can lock things through-and-to the chain. The Brute’s underrated because they don’t stand up well to weather, so they always get downmarked for that- and fair enough, but used inside they’re a very cheap, very solid lump of metal