Your going to love the Black ops especially if you played Call Of Duty WAW. Popular modes like Zombies returns with Black ops along a very influential character in the WAW campaign. MW3 continues on story wise where MW2 leaves off. The versus multiplayer
is designed from the ground up to be more competative with the new Call Of Duty Elite service. So it's a tough call to really say which is better.
They are both good games. I prefer Blops, but MW3 is far from a bad game. I suggest you rent them to try them out. And don't listen to Oasis. If he gets dominated by AI controlled killstreaks than he is just bad at the game. They are super easy to both
avoid and destroy. I don't use assassin, blind eye, or a rocket launcher and I can take them out without dieing with my AR.
If I had to go out on a limb and pick one, I would neither is "better" or "worse".
They are simply Preference in which one you will enjoy. Get them both, get neither. Do what you want. It's not a contest and there is no prize.
But then again, I haven't played either so what would I know?