Last week, I was having the same thoughts. I've been using Data Guardian on both Mac and iPad for years, but it's just a database to store credentials, and doesn't interact with browsers, which makes periodic password changing an order of magnitude more bother. I looked primarily at 1Password and LastPass.
I was initially considering the open-source Keepass, but it's a kludgy geek thing that requires several other third-party programs to make it work on a non-Windows computer. Well, allegedly work: after two failed installations, it finally stayed alive long enough to see how much more work I'd need to invest to get my existing passwords into it. If that floats your boat, go for it, but it's more complicated than I choose to accept.
1Password and LastPass are quite comparable in features, but LastPass is free for Mac, $12/year to synch over their cloud to iPad. 1Password costs about 3X that for both devices. Online reviews seem evenly split between the two apps. I went with LastPass, and spent several hours yesterday swapping about a hundred wimpy passwords for new random 15-characters strings, all unique. It sucked the old passwords out of my iMac's Firefox security file to get me started. So far, it's worked flawlessly. As a bonus, my preferred iOS browser, Mercury, includes a button to insert passwords from the LastPass database with one tap. No typing passwords! The only password I still need to remember is the one for LastPass itself. IIRC there's a Windows version as well.
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