I don't want to throw Mint under the bus: I used it for ~6 years before starting to work on Penny and it's a great tool for people that enjoy spreadsheets and crunching numbers (myself included). That said, it can be pretty intimidating to just to about everyone else. Penny requires a lot less effort on your part, since the number crunching is all done behind the scenes to generate cool insights.
To answer the specific question of why _you_ might switch: Mint hasn't really improved beyond the addition of more ads in the past four to five years. It's painfully slow (at least for me) and still has not learned that my gym membership is not software.
Can you talk about the measures that you use to protect banking credentials so that I might feel similarly safe about giving them to your service?
We never store any credentials on our system, and our access is read only. I can go on for days about why I think our system is more secure than, say, Chase[0], but if you trust Mint's practices it's probably sufficient to say that we use an almost identical system.
[0] https://en.wikipedia.org/wiki/2014_JPMorgan_Chase_data_breac...
I really wish banks could provide a read-only API token instead.
Check out PocketSmith. It may not have every feature I want, but at least it actually works. There is a nominal monthly fee associated with it, but well worth it if you want to actually use an online money analysis tool to do anything.