Have a Bernina serger with cover stitch. Although it's not self treading, it's not hard to thread and it's stitches are amazing. Plus it came with great lessons. Nothing sews like a Bernina!
I have the Bernina 1300MDC. It is easy to use and not hard to thread. I bought it used ( 1 1/2 years old but she only used it once in the first class from the dealer) but paid my dealer to take the classes that come with it. For 1/2 the new price it was a great deal. The stitches are wonderful! I really wanted a machine with coverstitch as I re-hem a lot of things as I am short - sleeves are always too long.
Bernina sergers are made by Juki and Juki has a similar model with the same stitches but no LCD screen.