I'm driving to California - should I get a Ford or a Chevy?
Both will do the job, each has its fans, and an active online forum community. Both are (incidentally) owned by Adobe, so the smart money is on one of them getting discontinued or sold off a la FreeHand.
Dreamweaver has the larger installed base, so it is likely to be the long term survivor.
I used GoLive until I got fed up with it corrupting its own site files all the time and crashing without provocation (so I have no experience with it beyond ver.3, newer versions may be more stable). Switched to Dreamweaver, which is none to stable itself, and has issues with text editing and slow table updating.
Partially, its more to do with your personal preferences. See if you can get some time on a computer with one or both of the programs. If you are considering getting the Adobe Creative Suite Premium with Photoshop Indesign, Acrobat and Illustrator, you will get GoLive thrown in "free".