For one thing - auditable source code. Except for my most paranoid moments, I pretty much trust AgileBits to not be selling me out to the NSA, but that'd be much easier to completely trust if the source code was public and audited/approved by smarter people than me who know their crypto shit.

Having said that, I'm currently storing my 1Password file in the unencrypted section of my DropBox storage, so my iOS devices can easily access it. (I've got EncFS/BoxCryptor working, but I don't think it's easy/possible to convince the DropBox app to read from the encrypted filesystem…)