I'm the same as most of the replies here, such that I definitely prefer smoking over drinking.
I tend to get a fairly solid hangover any time I drink enough to actually get drunk so I hate having to trade-off tomorrow if I want to have a drunken good time tonight. I did quite a bit of both drinking and smoking during my years in university so I don't want to hear that its just because I don't drink enough, some people just get hungover more than others.
Another reason why I prefer weed is because I love the fact that I can just pack a bowl or roll a quick j, spark it, and within a minute or so I feel frickin' awesome, whereas with drinking I've got to start shotgunning beers or pounding shots to start feeling drunk in a half hour. This also makes it a lot harder to moderate your level of drunkenness as theres the delay before the alcohol gets absorbed, and it can be easy to drink too much before they kick in, resulting in getting drunker than I'd like and then having to wait hours before I start feeling better. The bottom line for me is that if I drink too much I spend the rest of the night puking in some random location, yet if I smoke 'too much' I just relax on the couch or go take a nice pleasant nap.
Hahaha just re-reading that makes me laugh, I can't really think of a time when I've smoked 'too much' or actually wished that I hadn't just smoked that bowl/pipe/joint/blunt. I'm sure I must've briefly thought that right after some killer hits (6ft'er anyone?), but then immediately after that thought I'd bust out giggling while thinking "nah, who am i kidding?? this is fuckin' great!"
As I'm writing this I keep thinking of so many more reasons why I love pot over alcohol, but I will let others mention them. I think my main reason is the high itself, and the general happy and relaxed feeling thats comes with it. I guess its just that chill, laid-back, weed-smokin personality that some of us have lol