#1 on the Motobatt, the small G/S type has started my high comp 1000 cc G/S for seven years and still performs like new.
Motobatt also have a 20 AH universal model which might be a little cheaper and easier to find and this starts my 1000 cc R75/7 and R100GS fine too.
The big 30 AH BMW Motobatt starts my Subaru great too, but we dont get real cold mornings here -----.
In Oz they are half the price of the Hawker, so no contest.