Drum sticks are a very personal thing, with each player having a certain preference towards length, weight and tip size. There are no hard and fast rules when it comes to using specific sticks for electronic drum kits, so if you are unsure of what you are looking for, a good starting point would be a 5A stick.
These are the most commonly used sticks and you can pretty much figure out if you would prefer using a lighter or heavier stick by using this pair. As a rule, the higher the number, the lighter the stick. Generally, a 7A will be thinner and lighter than a 5A, whilst a 2B will be considerably thicker and heavier.
The sizing, weight and tip size/shape varies across manufacturers so it's usually a matter of trying a few pairs out and finding one you get on with. Nevada Music stocks a large range of sticks from Vic Firth, Vater, Zildjian and Tama, including a very popular line of artist's signature sticks.
So if you're still unsure of what to use, just get a pair of your favourite drummer's sticks!