My old zx14
after I put 11k miles on it going to Fairbanks and back from Austin. Extremely well engineered and durable machine. No one believes me except my buddy I went with but I did not adjust the chain or replace either tire on the entire trip.
2012 BMW F800ST I rented last summer while riding around Europe. Put 6k km's on it so I become very familiar with it. Props to BMW on their fuel injection technology, averaged 50 mpg on a fairly heavy 80hp parallel twin machine in mixed conditions including 1000 km's of 1st and 2nd gear 'trails' through the alps. In typical BMW fashion, however, a sensor screwed up and left me without an idle (had the joy of manually revving the bike at every single stop and during slow shifts) on my return trip across 8 countries.
My current and perhaps favorite bike (which is saying a lot given I've also had a 954RR, newer zx6r, suzuki 1200, yzf600r, etc.) is an SP2 RC51 with a full titanium race exhaust, PC, +3 on the rear sprocket, and a couple other misc modifications. The picture probably looks funny; I designed it for my capital one credit card which now has this picture on it.
God awful fuel mileage (25mpg mixed), the dual side radiators produce nearly unimaginable heat on your legs when it's above 90 degrees, and demanding ergos but the sound, chassis rigidity, overall suspension design (very steep rake), and raw character make it one of the most interesting motorcycles any Japanese manufacturer has produced IMO. Mine produces 150-155hp conservatively so it's plenty quick.