I tend to use 2 types of boilies, sometimes different sizes too. Although I have avoided 10mm lately, as the bream seem to like them on my current venue
As you say hook baits are a question of trial and error
I actually mix RH Monster Crab, KMG, and Infusion as my feed. All 3 are good baits. The original idea was to mix them and then use the favourite on the hook exclusively, but I've caught on all 3 so keep feeding and fishing them.