Lots of good answers already. It's basically personal preference, plus the consideration of whether you need your gloved hand to do anything (whether you load with it).

I personally load with my left hand for air and 3P shooting, so my current glove of choice is the Gehmann 465, but they're all really variations on a theme. Best thing to do is get into a shop and try as many on for fit, materials, etc (if you're down at Bisley ever, the NSRA Shop there has a broader range. Not sure why they don't do more with the Aldersley site - as you've found out, they've got the facility there but aren't quite investing in making it a proper target sport centre with a decent shop or anything).