Go ask the dealer to let you look at a service manual and turn to the engine section. The engineering on the Triumph is first rate while Japanese bikes are designed strictly to be made more cheaply than possible.
Next, go look at the price tag on a typical Harley, about the same as a Speedmaster AND a Speed Triple. They are well made for the most part, but not that well made.
Then, there's the matter of personality. A Triumph has a personality like an old friend. A Harley has a personality like a rowdy hooligan. A Japanese bike has a personality like an apartment size refrigerator.
