While I respect TheMasterCavers opinion I would go infinity at first. That way you don't need to haul stacks of arrows around. Look at the end of the day though it comes down to how often you use bows.
Personally I make more than enough experience mining to ever need mending on my bow. Go with your heart. I never need to repair my picks or sword as they have mending. I use all my extra levels to repair my armour. Because I already had a mending and infinity bow pre 1.11 its not a concern for me. If I did not have it I would use infinity and spend some mining xp on the bow.