Hello :-)
Why would you choose breadwallet over mycelium? does it have any extra features that make it much better?
Cheers
If you're looking for a good mobile wallet to use, I personally love using breadwallet. The main selling point for me is that it is able to connect directly to the blockchain and can see in real time how many peers are confirming your transactions and when exactly if it's confirmed. If you think that a transaction has been lost, you can always rescan the blockchain on their, which makes me feel a little bit more secure when transacting money around. Plus it allows finger print scanning to quickly access your wallet, which is always a plus too.
I've never personally used Mycelium, though I hear it gives you access to your private keys which you can write on a piece of paper and store away; just like with breadwallet... but I'm not quite sure if Mycelium connects directly with the blockchain, which is why I've always stuck with breadwallet. It's just my personal preference, I've heard a lot of users on this forum like Mycelium too; I think both are very good mobile wallets, I just tend to stick with bread because of the "if it isn't broke, you might as well not fix it" mentality I've got going on.
Mycelium uses a few centralised servers to get the information from. They can trick you into accepting a double spend. Last time I saw, they have 3 nodes. This isn't a huge security issue since wallets like blockchain.info, CoinBase, Greenaddress.it all uses central validation. I don't particularly trust biometric authentication. After all, people have exploited iPhone's fingerprint sensor and people can knock you out to steal your Bitcoins.
My vote would go Electrum. It has a cold storage spending feature and is relatively decentralised since you can select your own server to trust. The Hierarchical Deterministic seeds is a huge plus since users only need to make one and only backup to be able to recover the coins. Clients like Bitcoin Core requires backups every 100 transactions.