I prefer MoMF if you want to wild shape into vermins and get Ex abilities. However, if you want to keep your spell progression, there's various forms of poison among vermin, though they generally aren't very impressive. The monstrous spiders' web ability can come in handy if you need some battlefield control, and the centipede has a monstrous (pun not intended) grapple score (But you'd get that anyways. No need for Ex here.), although for the really good stuff you'd need to be able to become Gargantuan or even Colossal. Just never, ever, wild shape into a giant bee. And if you do, never, ever use your stinger.
All in all, I think you're better off wild shaping into stuff other than vermins.