Well, the simple answer would be Slaanesh. Slaanesh is driven to excess, and his followers often are portrayed as hedonistic.
To go a bit further, Khorne is interested in besting others in combat. While certain stimulants might make a warrior more capable in combat, they wouldn't be testing their own might against another... they'd be testing their augmented abilities against another, and that doesn't prove their superiority, therefore Khorne would not want to use drugs.
Tzeentch is the changer of the ways, and is portrayed as a schemer. Depressants slow the mind, which isn't all that great if you're trying to outwit someone. Stimulants have a habit of clouding one's judgment, which again isn't that great if you're trying to outwit someone.
An argument could be made that Nurgle enjoys a certain disregard for unpleasant things, so he might be into depressants to further mellow himself. Stimulants tend to be, well, stimulating, which tends to make people feel "more alive". That's probably not his thing. I could see a Rastafarian-like appreciation for certain plants, owing to his general good cheer and seemingly easy going attitude.
That said, I'd have to say it's a no brainer to go with Slaanesh Higher highs, and lower lows, are pretty much his domain.