Shoes and boots are a personal fit ‘thing’. The safari boot, is a common design, that’s been around for longer than either of the boot makers, in question, have been making boots.
I have no experience with Courteney boots. I know people, whose opinions I trust, who swear by them. I do have a lot of experience with JL safari boots and I swear by them. What can be concluded is, everyone needs to try both brands and choose what fits them the best.
FWIW, Crispi Nevada hunting boots are the best general purpose hunting boots I own.