I only became aware of them at the time of the Joshua tree and I never really heard the comparisons. U2 seemed to me more traditionally rock based while the Bunnymen were a little more out there, more moody, more atmospheric. I was a U2 fan up to Achtung Baby (still think The Fly is a great, great song) but they seemed to lose the plot after that and Bono became a bit too preachy for my tastes.
It's funny though all the U2/Bono bashing Mac has done and continues to do and the band (and Bono in particular) have been by appearances complete gentlemen. Even after Bono said that Mac was always better but U2 had better management, Mac hasn't backed off. I loved that quote about not wanting U2's fans. I gotta call bullshit on that one. I think Mac would love to sell that many albums. Isn't that what the Fountain is supposed to do?