My favorites are actually a combination...
Black & Tan (Guiness/Bass Ale)
Half & Half (Guiness/Harp)
Get someone who knows how to pour them correctly from the tap and they are just awesome!!!
I collected imports, (Non-USA) **** bottles for a while in my first apartment, ending up with about 175 taste tests. Kirin, (Japan), Krakus, (Poland), and Grolsch, (stopper top only), were good, but I always come back to Heineken.