I also have the Bernina L220 coverstitch. I've had her for 3 years now (it was phased out of the Bernina range at least 1yr or more ago - more on that below) and we're still good friends. The looper tension has got a little looser with age, which isn't a bad thing so I really don't do much tweaking. I use her mostly for knits - the lycra dance dresses, but not exclusively.
I use the chainstitch quite a lot. Of course for basting it's a dream with a quick unzip afterwards (easy enough to secure when you want to as well) but it's also good for a bold single line topstitch if you sew it from the wrong side. If you need the stability of a topstitch but don't want it to show, it's useful to stitch in the ditch and still have that bit of stretch when needed. I've also found it excellent for using on dress net. Since my DGD has been in adult sizes I can't get a ballroom single circle skirt in one piece when I can't buy 300cm wide dress net. The chainstitch is ideal for seaming two half circles of net, a really strong seam that you can press open making it both less visible than the serger and more robust than a plain straight stitch.
As for the machine. The L220 was the last Bernina model made for them by Juki. Once Bernina split from them and moved to Jaguar, Juki finally brought out their L220 design branded under their own name. I haven't tried the new
Bernette coverstitch but the Jaguar sergers that I have tried were very unrefined beasts so that combined with the Bernette branding doesn't fill me with confidence in these circumstances. In the meantime all the glowing user reviews of the Juki MCS-1500 twin have helped Juki take the home coverstitch world by storm, the number of people buying it purely on recommendation without trying it is impressive. It's really leading the charge for Juki in the US.
I've not used a Babylock although I've seen them demonstrated and it seems to me that is the other machine that is most comparable with Juki. Babylock owners would insist it's superior I'm sure, it's certainly more expensive - some of their combination models being very much more of course.
Many Janome coverstitch owners have great results with the 2000cpx in particular but it seems to be less friendly than the Juki/Babylocks and needs some patience and determination to get used to the greater attention to settings that it appears to need. They all have a learning curve and may throw a real hissy fit with some fabrics occasionally but the large number of former owners who report they've sold their Janome and then replaced it successfully with the Juki or Babylock may support this assumption.
Brother have a couple of coverstitch models, one of which does a reverse coverstitch (where it can produce the looper stitching pattern on the top surface). I get the impression that they are similar to their sergers - certainly a similar plastic feel with lots of vibration and noise. One sees lots of problems popping up with new users on the coverstitch groups but you'll also find that to a lesser extent with both Juki and Babylock at times as they do require a greater understanding than an ordinary sewing machine (it doesn't help that Janome & Babylock use different needles to Juki & Brother) but for many of us they have just worked right out of the box...until you eventually discover that one particular fabric it absolutely hates.