In order of my favorites:
1. Mariah Carey & Nick Cannon - They are so in love and NOT afraid to show it! He is such a gentleman and always defends his wife!
2. Khloe Kardashian & Lamar Odom - These two are blissfully happy. LOVE them!
3. Will Smith & Jada Pinkett Smith - Such a down to earth, real couple!
4. Beyonce and Jay Z - Only because I like them as artists. They rarely even look like a couple to me and hardly ever publicly show affection, which to me, is just ODD
5. LaLa & Mello - How cute is their little boy Kiyan?
6. TI & Tiny - A couple that breaks the law together, stays together (*scratches head*) I guess
I know I added some couples that weren't on your list, but these are my favorite Hollywood couples!