I purchased the TOL Bernina Serger almost 30 years ago now and it's still going strong. I want the BabyLock Evolution but just can't justify it. As for the air threading etc.. that would be nice but it's not necessary. Almost all the sergers are fairly well labeled on the paths to thread.
If I didn't have a serger I would purchase the BabyLock Evolution but that's me. I've spent a number of hours test driving the various machines and it is a very very nice machine. So the most important thing is for you to spend a great amount of time testing. Define precisely what you want (write a list!) and take that with you when shopping and grade each machine in each area. Then you will know what is a fit for you and your pocketbook.