I hate mint but use a different budgeting system. I'm not sure you can compare an accounting system with a budgeting system - they serve different purposes. I'd love to build a full budgeting system on top of one of these text accounting systems some day.

Just create a "Budget" account and a report that does "Budget" vs "Expenses"

Beancounts budgeting system is fairly poor. It can't handle envelope budgeting, which is the only useful budgeting system I've found so far.

For envelope budgeting, I just make subaccounts of my bank accounts for specific purposes.

It's not great, but what I do is create a fake expense far into the future...