I had an old White serger for 20+ years and basically outfitted my children with it! Lots and lots of little pants and tshirts and sweatshirts. Nothing like a serger for knits. The old machine didn't have differential feed so I had to be very careful not to stretch things, but it still worked. When that old machine finally died I bought a new one. My requirements were that it have differential feed and be easy to convert to a rolled hem stitch. I ended up with a Bernina 1300MDC that I get along with just fine.
In addition to clothing, I have made all kinds of home-dec stuff with the serger - pillows and curtains especially. It handles heavy fabrics that fray very well. I also have made dozens and dozens and dozens of rolled hem napkins out of wonderful fabrics - one of my standard wedding shower presents. I also use a rolled hem edge on flannel receiving blankets.
As to ease of threading, a lot depends on just how handy you are. I thought about an autothreading machine, but it just didn't make the "most important" criteria for me. Most of the time I just pull the threads through when I change colors so it doesn't take long. Even if I need to rethread from scratch it only takes 3-5 minutes for a 4 thread, and half that time is doing the regular needles! I do recommend differential feed though - that is a great help on knits.
Pam