I'm no expert, just an enthusiast, but I have tried a number of the choices in the thread so I might as well put my 2-cents in.
I agree on the El Dorado swap. I could hardly tell the difference between the 12yr and the 15yr. I actually had some guests do a taste test on this at a party a couple years ago. One guy, who doesn't know rum that well, picked it out right away, and a bunch of others simply kept asking for more of both! At any rate, I can barely tell, if at all. It's a good rum but not my favorite. (I love the Mount Gay Extra Old the best as well!)
Personally, here's my list:
1) Mount Gay Extra Old- got to have that. Perfectly blended rum with just the right barrel hints. (My choice of back up here is the Cruzan Single Barrel- just a fantastic rum, in my opinion)
2) Ron Zacappa Solera 23- unique flavor. Very interesting complex flavor. It's truly a special rum and probably would be my favorite if not for the fact I got used to the MGXO long before.
3) I like the Goslings Black Seal a lot. As others have mentioned, it is great for mixing with ginger beer - Barrett's diet is my favorite, followed by the Goslings. I also sometimes mix the Zacappa with it (sorry if that offends anyone). Tastes great.
4) I'd recommend the Rhum Barbancourt 8yr as a great choice for zesty flavor. I have a bottle of the 15 as well, which is pretty incredible, but I think the 8yr is the best 8yr I've tasted so that is my pick. It's such a great flavor.
5) For the sugar cane style, I'd pick St. James Extra Old Rhum- it's really good and much cheaper than the La Favorite Rhum Agricola Vieux, which I believe is over priced. The Saint James Rhum Ambre is a decent little rum too and it is a 2yr.
Maybe I'm showing my naivety with my list, but that's how I'd go for 5.
Adding a lighter rum for 6) Westerhall 4yr.Plantation Rum. Very unique flavor and very good.
Finally, if we go with the British type, I'd pick the Green label Cadenheads. It tastes very different and a bit harsh, but it has grown on me over the years and when I drink it, I know who it is, you know what I mean? Very true to self, that one. I actually have some of the 15 yr siting on my shelf still, but oddly enough, I like the roughness of the 4yr better, as they both retain the same unique flavor.