e5 or e10

My cb has been laid up a year and a half ........ I spin the engine every couple of months .......... trickle the battery ...... the petrol is now a year and a half old at least ( I may have topped it up,can't be sure but definitely at least a year ago) .........
It starts first time always.
Should I just leave it or replace with e5 after draining tank?

Any advice welcome.

Loathe to sell the bike as it's just so reliable and sounds great!

Depends on how often you use it, if laid up for more than a few months I will fill up with E5 preferably Esso as in most cases they say their E5 does not have any Ethanol in it, failing that make sure tank is full and drain fuel from float bowls.