I've gotten some very angry reactions to this of the flavor "WTF you think design doesn't matter" and "this'll never work at a bigger company". I get it, but please hear me out (and read the whole post) :)
Yeah, love that Sam. I'm not much a github user myself but if there's some existing body of best-in-class templates I'd love to be a part of that. For me, it's all about having a quick thing bookmarked that I can just duplicate from.
My wife is a CPA accountant and I'll go out on a limb and say that 80% of her time is spent doing the equivalent of data cleaning and validation. The balance of her time is making judgement calls so she can appropriately reconcile notional rules against the messiness of real world business transactions.
Keeper Tax is very user friendly, but designed for a simpler use-case. It only does expense tracking very well, but it doesn't have income tracking, or invoicing.