I rarely watch Twitch much anymore since MLG.tv took most of the pro cod players away from it. I get a kick out of watching pros play mainly because of the skill level. While a few of them are fairly boring personality wise, I think you'd be surprised at how entertaining and funny some of them can be.
For me, watching cod streams is much like tv used to be for me. When I sit down to eat a meal, I turn on MLG.tv or twitch and watch pro's play wager matches or scrim other teams. I like the competitiveness of their matches.
Twitch is by far the better streaming site though. MLG just has more of the people I watch regularly.
My favorites to watch are Scump, Formal, and Phizzurp.