Dumbbell bench requires more stabilization muscles, but you'll be able to build more raw upper body strength with barbell bench.

I did dumbbell bench exclusively for close to a year, and got to the point that I could get 5 reps with the 120 pound dumbbells. However, when I moved over to barbell bench, there was surprisingly litte transfer - no real difference from where my barbell bench was before I started doing dumbbell.

Absolutely agree on squats and deadlifts. Squats should be the cornerstone of a strength program.