I tend to vary the bait I put on depending what others on boat or catching on. Think Macky is a decent all rounder and I always take some on board, but always as a preffered bait, use worms, squid tipped lugworm is my favourite combination.
Have heard peeler crab being deadly for catching cod, but the few times I have used it, I have had pretty much the same catch as I would do on rag/lug/squid/macky/bluey.
Have heard that them peanut worms are meant to be good for catching, you get them through Glasgow angling centre, but don't know anyone who has used tried them yet, so cant give an opinion.