I love all the weird ones, the American more-of-everything styles, the barleywines, the crazy belgians, etc. That said...I have a very strong affinity for British bitters, milds, and pale ales. The best of these seem to have a perfect balance between modest hopping, really tasty malt character, and yeast esters that straddle the fence between the strong notes of Belgian yeast and the very neutral character of American yeast.
In short, British ales are sublime and wonderfully balanced. Marstons Pedigree Bitter would be my desert island beer. If I had a good clone of that on tap all the time I'd probably gain weight in no time...