Depends on what you are using it for.
If a dedicated starting battery (like I am going to have) and have a house battery dedicated to running my electronics, pumps , etc, then I would us ea deep cycle for the house.
If you plan on just going with a 1 battery setup, then get a group 27 dual purpose.
IF you have the funds, the Cabelas Group 27 (even the group 24 since it is fairly close in spec) is REALLY the way to go.
Lots of guys who are running Optimax and Verado engines are using it (and those engines spec a MUCH higher cranking amps then most other outboards).
If budget is a concern, go with an Interstate.
Rmemeber, having onlya 1 battery setuo, you will need the battery to crank the engine, then provide enough slow juice for running fishfinder, radios, pumps etc when drifting with engine off.
That is why they make the dual purpose.