We have built Buxfer to cater to power users, so it has lots of powerful functionality - budgeting, forecasting, automated rules, investment tracking and so on.
GP's feature set sounds like its for "superpower users" :) We don't (and will likely never) get too much into things like taxes. But Buxfer is still one of the rare products that has a simple straightforward pricing and caters to a niche that expects powerful features from their financial software.
Disclaimer: I'm the founder.