Personally, we don't handle any of our bookkeeping or accounting but we have tried the following accounting software ourselves and also prefer Simply Accounting Pro Vs. Quickbooks. Our Accountant uses Simply Accounting Pro. In addition, our Bookkeeper is also using Simply Accounting Pro. If you're planning on doing the bookkeeping yourself then I would suggest Quickbooks. I found Quickbooks is more for business owners who want to manage their own work, 1-3 employees for payroll etc..
With Simply Accounting Pro, when doing account reconciliation you can enter an unlimited number of expense and income transactions which is a plus! and there is a nifty module that allows you to easily remit payroll deductions. However, should you make an error with Simply Accounting Pro, the error cannot be deleted or revised. Instead, you'd have to do a reversal entry. What does this mean? You can't hide any of your work.
If your business is simple, I would go with Quickbooks since it's cheaper, easier to use and gets the job done. From an accountants perspective, we've heard that Simply Accounting Pro is technically a better system Vs. Quickbooks.
WHMCS is great at keeping transaction records but personally, i wouldn't consider WHMCS actual bookkeeping software. Hope this helps and good luck on finding the software that's right for you.