Apilife Var and Apiguard are both based on Thymol. However Apilife Var is easier to use and similarly effective. I used to buy large tubs of Apiguard as it was cheaper than the single use foil packs but now its not available in those tubs for some strange reason, so Apilife Var is preferable to me.
Oxalic Acid sublimation needs protective equipment for the user as the fumes are nasty, as well as you need to buy a relatively expensive tool and battery, so I would not recommend it for someone with a few hives.