Hi Jeff,
Microbore is suitable for most applications and would be recommended by us as it is lighter and has a more suitable flow rate for WFP.
A few set-ups find that Microbore is slightly restrictive or upsets their flow rate/pump settings. For these users, Minibore is more suitable.
Most hoses are sold with the Internal Diameter size indicated, so if yours says 8mm that will probably be the 8mm ID Minibore.