Bumble bees and humans have different preferences.
I’m spoilt for choice, as are the bumble bees, regarding flowers in the allotment borders at the moment. The sweet peas are just coming into flower and are one of my favourite summer flowers. To me it’s a toss up between them and the majestic delphiniums. For the bumble bees however the clear winner is the comfrey with sweet peas coming a distant third.