I have a Brother 1034D serger. I bought it from recommendation from my sewing teacher when I started to sew. I checked it out online and it gets 5 star ratings. It was cheap at CostCo.com. Hubby bought it as a surprise when I mentioned it would work great for knits. It not self-threading, and threading it is hard -- especially when I have to use reading glasses to see. Teacher recommended getting those disposable dental floss thingees to assist, and they do help.
A LQS I have taken other classes as is doing a serged quilt now. I asked what the advantage is (thinking it would use more thread and be harder) and she said it easier to square and press. I didn't take the class.