actually only do manual breaks or no breaks at all builtin bots break handlers are easyily detectable so it is never advised to use built in breaks but manual ones. Also you can babysit it now and then but not too often
I think that Arbi's is better but the randoms aren't as good. I normally get more from Arbi's/hour than the Nexus one.
I recommend checking out Proggies of both of them and comparing, Remember that running Arbi's without watching isn't a good idea due to getting stuck in randoms alot.