Important to put handling and climb performance in two adjacent paddocks.
(a) Vmc - VERY bank dependent. Not hard to find aircraft with a 30-40kts increase in Vmca if you bank the "wrong" way. The certification limit of 5° puts a constraint on the innovative OEM. I suggest that, if the book doesn't say different, presume that the AFM Vmca figure likely is based on 5°. Back near Vmca one is interested in not dying immediately so handling is the name of the game - performance sits in the wings at this time.
(b) climb performance OEI will be maximised somewhere near the condition for zero side slip (think about it - what's the easiest way to generate a bunch of drag and an increase in descent gradient in a light single overshooting the runway on approach ?)
It turns out that zero side slip occurs around 2-3° bank into the operating engine(s) for pretty well all multis (337 etc notwithstanding). Given that flying this sort of bank angle is demanding on the pilot (and, for some aircraft, can't be done due to AH limitations) the oft-chosen compromise is to fly wings level and accept the small climb penalty. It follows that 5° bank is going to be somewhere near the climb capability found for wings level so there is no point in trying to climb at 5° once you have the aircraft established in the climb at an appropriate target speed in excess of Vmca. If the aircraft is light enough to achieve an impressive OEI climb, go for wings level anyway.
(c) Vmca region - go for 5°. Established in the OEI climb wings level makes good sense and, if you REALLY want the last bit of climb (and you are smooth enough to do it well), go for 2-3°