Regular most of the time...every now and then premium non ethanol. A couple ounces of Seafoam every once in a while leaves the exhaust smelling minty fresh!
The older bikes like ours are made to run on 89 mid grade. Mine never liked it. I buy 91 alcohol free and when I cant get that I buy 91 10% Chevron or Shell. The newer bikes are made to run on 87 regular.
Check your Owner's Manual. The 2014 manual say to use regular. But use top tier fuel (Shell, Exon, Mobil, Amoco) as they contain the most cleaning agents in the gas. Triumph says not to use additional cleaning products.
I wish I could get low octane and no ethanol, but alas. But I run the lowest octane available to me, stock this engine needs nothing more. It's not very high compression, so why put in fuel that explodes *less* willingly?