#4 'may' be too young for a corporate audience. Not sure about a fat purple wasp ;) but like it's playfulness #3 Don't mind the radiation post really. Maybe as the 'i'? Or too cheesy? Bolder bigger font? #2 Reminds me of the Tax logo in the UK. Scary! I don't get the thinking behind this one but like it's boldness #1 A radiating blob works, would like brighter colours. It's a bit dour BUT for corporates I understand it cant be neon!
My faves are #3 and #1 but none tickle me completely...