My first serger was a Brother 929D, a cheapie from Wal Mart.
I bought it several years ago, and it is still going. One of the features that I love about it is the free arm. That part is great for doing cuffs and hems on jeans/pants. I mainly bought it to give the inside seams a professional finish when making denim shirts for my guys. I bought a pfaff 4874 but honestly haven't used it much so far. I did topstitch some scrubs that I made for my daughter. It makes a great coverstich.
As far as ease of use and simplicity, I still like my 4 thread brother though. Will warn you folks who are not accustomed to threading sergers, be prepared to learn how.
Once you 'get it' you will be fine, until you learn how though, you may pull your hair out.