Hello!
I, too am new to this site and just happened to see your question. I have worked in a sewing store for the past 3 years and here are my thoughts.
First and foremost, research before you buy!! Second, as someone else recommended, make sure they demostrate the threading process no matter what model you buy. Ask if you can do it. The jet-air by Babylock is very nice but be ready for sticker shock. I personally own a pre-owned Huskylock (Viking) 910 and love it!!!! Even the owner says the 910 & 936 (has cover stitch) are the best. It is really a personal perference. Another thing is service!! Wherever you buy your serger, check to see if they offer any training classes and if they service their machines. I know Viking just came out with a 200S that sergered nicely. It's brand new. Have fun shopping!
Sergers have come a long way since they were introduced. I almost bought one 30 years ago but decided to wait and I'm glad I did. I love my serger and it isn't something you will use ALL the time but if your area offers classes for projects using using it, you will be surprised. I make a serge/flip baby blanket that is done completely on the serger. AMAZING!!!! I've also made a tote bag totally with my serger except the finsihing top-stitch. I have not used it in quilting but have no doubts that may be ways you can.