[WhiteOwlLion]

Filing for sole proprietor is really easy. You just make estimated tax payments. It really depends on how much income you generate. If you file quarterly, you're doing well I think.

Accountant can do more than taxes, so they are more like a business ally. Tax agents can file taxes for you and represent you if there's any tax issues.

I've been able to get by with Quicken & TurboTax for sole proprietor.

For LLC, hard to say. QuickBooks desktop or online seem to be the most common. It really depends on how complicated your business needs are I think.