That's a very general comparison Mya. There are many more factors than just those two. Storm Giants can do very well. Remember this also folks, Zerks are not the best at solo gearing themselves after a loot either and being a good aligned for the ability to request things makes that much easier for someone just figuring out the class.
The most important things in my eyes for a zerk are in order: 1. Weapon selection vs. Class(You know nearly all of them, so no reason not to use this). 2. This also entails knowing a bit about your opponent and their gear relative to your own. Some hybrids and rogues can deal a fair amount of damage if they are dressed better, so you might choose two handed over dual wielding. 3. Tactics, and this is again relative to number 2 for depending on each situation you might get more mileage out of certain skill progressions(I.e. vs a warrior better dressed than you, dirt/flee and outregenerate with a random haymaker or cleave. As Ototh I almost always opened against c/c's and blademasters(haymaker only) with haymaker or charge, usually haymaker.) Even if they are better prepared than you and you can run them out of buffs before you do yourself, your chances of winning are much higher. There are MANY more aspects to the class depending on your playstyle, offensive, defensive or a mix, etc. It will take time to figure out but once you have some practice against all the other classes you will do very well. There have been a few successful zerks and from discussion and experience each has had their own favorite tactics in certain orders for certain classes. GL, see you IG.