In my personal preferences, Guiness, at 65°F, follorwed by Imperial Extra Stout, Little Kings, Grolsh, Dos Equis Negro, and Fosters. If you can find it, Hamms Dark is pretty good, too...
IMTU: a couple more for your consideration
Wypoc Ale: "It'll Eat Ya!" (Made from fermentates of local flora... both dome and wild... then filtered for safety. Novelty beverage. Mildly acidic, mildly toxic.)
Ol' Scruffy's: A Vargr beverage line. The beers include pinapple-Habanjero, Skymellon rind, Howood nut, Jalapeno, Black Pepper, and Groat Blood. Wines include all the above, plus an exquisite (if little known) Zilan Skymellon vintnery. Old Scruffy is a cultural vargr in a human body. Also, all the above are made into cordials, as well. There is also Pepper Sauce... Take a miscelaneous assortment of local grains, and some Habanero, ferment, distill at careful temperature to get the volatiles from the habanero as well... then age in barrels with habanero and jalapeno pepper seeds, on the coast of a Zilan sea... filter and bottle.
Scout Grog: make your mash from flour, pure sucrose, and water. Cook, add yeast of choice, then decant into carboys, distill when fermentation stops, ususally by freeze-distilliation, so as to get a weak whisky. Age about a month, in fresh carboy (the one you just washed since it was empty, and drained into leaving the ice in the first one...), with whatever fruit rhinds are available thrown in for flavor. Package half for self in 0-G fluid tubes, sneak rest to favorite scout bar for the discerning customer... usually for a few small credits from the proprietor.
JarHead! A flighty cocktail of hard liquors, vagely fruity, with a sharp pepper bite, all cut by 50% groat milk. Served chilled, if served by labelling. Marines tend to turn it into instant toddy: have the barkeep run the tray of unopened bottles through the dishwasher immmediately before serving. Label shows a marine holding a jar containing a pickled head with scout service like headgear...
Fizzyglug: Reginan non alcholic intoxicating beverage. Massive health warnings, mostly true. Posession on base forbidden; consumption off base limited to no less than 24 hours before duty. Toxic to Virushi; induce vominting and contact poison center immediately (Difficult hazardous fateful endurance for the virush to avoid major systemic failures...apply mishap results to random major internal organs...). Does little for aslan. Safe in small doses (1 can) for hummans and vargr, being Mildly euphoric, hyper sensitivity to touch, and lazy (Routine Endurance and Carousing to avoid intoxication on first drink, second drink rasies to Difficuult Hazardous, and eacch additional increses difficulty by one step. Each dose lasts about 4 hours. If task failed but not fumbled... apply a +1 difficulty shift to all tasks; sucess results in a 1 point penalty to mental attribute DM's and skill DM's, Critical success results in no penalties.)
Hmm... maybe my player's characters are drinking too much.....