Internet Explorer: No encryption or master password.
Firefox: No encryption, master password.
Chrome: Encryption, no master password.
All of these browsers, no matter how you put it, can be hacked by anyone with physical or remote access to your computer.
A browser being open-sourced can go either way in a security debate. On one hand, it's bad because then people will know how it encrypts the password and hack it easier. On the other hand, if it's open source, it'll be more rigorously tested and modified, and hence, much more secure.
My solution is to use a password manager with some decent encryption. Keepass (Windows) and 1Password (Mac) are known for having the best encryption (128-bit Rijndael, though KeePass hashes the password a lot so technically it's way more secure). Both of them have viable browser integration and should be fine for general surfing purposes.