I must admit that i have no idea sorry Tom. One of those things where you get what you pay for pretty much. The more you spend initially the longer before you want a better pair

Best thing to do is try them all out so you can see for yourself. It won't take long before you will find one will suit you better -whether its better low light or purely sharpness or even how easy they are to focus etc. I wear glasses so this is a bigger issue for me foe example.
Do you know what all the numbers mean? eg 10x25?