Dumbbell or bar bench press?

i do both, the preference being not having to switch too many plates around my equipment before starting... so whichever was left with the weights closer to what i need them to be gets used... yup, i am lazy
i'd say it's easier to watch form with the barbell. but whether that is a pro or con, each one has to decide for themselves.
as for the weight difference - are you accounting for the weight of the empty barbell or just counting the plates added to either?

Typically 45# extra for the bar.

Typically 45# extra for the bar.

depends on the bar. according to wikipedia, a women's olympic bar is 33lbs, and "standard" bars are somewhere around 2.7lbs/ft.

The bars in most commercial gyms will be around 45lbs (give or take for shoddy/cheap manufacturing). The women's bars are just shorter version and few gyms actually have them. Then there are specialty bars which I have only ever seen in one gy. These have various weights up to 100lbs each.

Also, "standard" bars, generally refer to the bars that are 1 inch in diameter, not the Olympic style ones you see in gyms that are 2 inches.

I find it advantageous to do both.

I can do more weight over a larger range of motion with the bar (110's+ start to get cramped for space), but obviously using each arm independently helps keep both the same strength.

I also tend to use my chest more than my triceps and shoulders with dumbells vs. the bar as the range of motion is a tad different.

Another disadvantage of dumbells is that you can't really do low rep sets as it takes so much effort to get them into position to press. 6 is about as low of reps as I'd even fathom in that reguard.

I have bad shoulders and Dumbbells allow me to rotate my hands facing each other for the press which is much easier on the shoulders. I switched to DB several years ago, but occaisionally do Barbell to see if I am retaining strength --- so far so good even though the combined weight of two DB is far less than the barbell weight I used to use in my workouts.

DB's can improve stabilization and coordination. I prefer DB's for many of the same reasons as other posters.

http://www.mensfitness.com/training/build-muscle/dumbbells-vs-barbells

That link pretty much sums it up. I have a feeling the OP is more like me at this point and dealing with dumbells that are so heavy they're cumbersome to deal with is a problem I won't have to deal with for quite some time. Personally I primarily do barbell for flat bench, but alternate if I'm looking for something different.

I use dumbells mostly, but really it stems from the fact that too many guys camp out on the peck deck and getting to the bar is tough.

As for the point people make about the stronger hadn being able to push more with a barbell, least you forget the weight will shift when one side starts going up faster or higher than the other, so much of that is mitigated and failry even. The bar also uses less ancillary muscles for stablizing compared to dumbells so it usually allows for more weight and easier handling.

Of course, using both is optimal.

When I had a gym membership I used both. Now I only train at home but don't have DB's heavy enought to press with. So I use a bar and do decline, and incline press.