I'm very heavyweight. Unless I have A LOT of money - I can't get drunk in a pub / bar unless I've been drinking before I come out. A 700ml bottle of vodka / Jack will get me pretty drunk, or about 12 pints. But I can go a full litre of 40% spirit without passing out or being sick.
It's a combination of the fact that I'm tall (6'2), male, come from a long line of heavy drinkers, and the 2nd time I got drunk it was on a full bottle of Jack (I nearly died that night, fell on my head and got a concussion) and that jump-started my tolerance levels.
I;d personally rather be a lightweight. For one it's cheaper... and secondly, for me to get drunk I need to drink loads... which equates to KILLER hangovers.