Red wine is usually the worst for hangovers. I used to think that was because of all the assorted aromatics that gave it the color and flavor intensity but subsequently heard that an additive is the worst offender. I think the problem is the sulfites they put into a lot of wine. In order to test the theory it may be necessary to experiment with wine of a sufficient quality that it doesn't have all the sulfites in it. For research purposes only, you understand
On a more serious note it's been a long time since I had much of a hangover simply because I don't usually drink a whole lot. Beer tended to give me the most hangovers although that was because back in the days when I did drink more copiously than I do now beer was my tipple of choice. One thing I found interesting was the way some drinks had a greater or lesser effect than others - I always used to find that whisky had very little effect on me while even a small amount of vodka had far more effect.