Okay to be honest this is how I usually do things.
Water= any cigar that is extreamly flavorfull that doesnt require any sort of "help" or a cigar that I havent had before that is supposed to be fantastic (another example is a cigar that has very subtle flavors that I don't want to miss)
Diet Pepsi= I don't feel like drinking and I want something more than water to either help the flavor or maybe to mask a bit of the strength (usually to help the flavor as I have been looking for more and more full bodied cigars cause they just don't pack the PUNCH they used to for me)
Hennesy XO= I drink this EVERY time there is a special occasion or I feel like a GOOD cognac with my cigar, usually I will choose a VERY strong cigar to go with this drink and 99% of the time it is an ISOM (exeptions to the rule have been a La Luna and a trinidad that I had that were VERY good) that I have had previously and noted to myself that a good drink would not overpower that cigar.
Other cognac XO and otherwise= I have MANY diff. kinds of this stuff and drink it with no reason or even too much thought behind it, I tend to just drink these and then smoke a "dog rocket" or try a new cigar that I really don't think will be good (anyone noticed that very FEW cigars are good after that pre-concieved notion?) or a cigar that is supposed to be "premium" that doesnt fit into that catagorie in MY book.
Scotch= to me this requires a cigar I know HANDS DOWN and I want to see how this or that scotch will compliment the cigar. I don't know much about scotch except that I like it and will keep an open eye with all these reviews going on and such (thanks AVB for really being on top of that)
I stay away from flavored soda and cofee (not that I really drink it too much anyway) when smoking a cigar as they tend to ruin even a good full bodied cigar for me.
But as it has been said before TO EACH HIS OWN!
Phil