Actually, I prefer the marine shotty over the TOZ. I just find the sight lines up easier for me. However, my favorite weapon? That's a decision between the M9 and the Makarov. "But, wait! Aren't those the pistols?" Yes. So far my favorite thing to do is run around dust2 and kill people with pistols. Sure, the shotty is fun on that map, but it's too easy. The pistols make it a challenge and a lot more exciting when I actually get kill streaks. The problem, though, is that most classes only get two clips. That's, unfortunately, why I go for RPG or grenadier because the M203 gets a third clip and the RPG has FIVE!
Now, if I want to actually do well, I use the AK-74 or the M16. For some reason, the 74 seems flawless in my reactions. I think it has just the right amount of sight to work. The M16 on the other hand used to be my absolute least favorite weapon (it's actually why I started running around with pistols). But, what I've discovered is a single well-aimed burst will take someone down. It has very little recoil, so you don't have to take any of that into account. And, most importantly, when you can nail four people in a single room with an M16 between before they get a chance to react, you know that when you pull out the 74 people will cry.