personally, I would go for the Bernina, I am a sew professional and own 2 Bernina's; my workhorse and my serger are both Bernina's; have had them 20+ yrs with little to no servicing and use them day in and day out........great machines!!!!
Now; a great tip about threading your serger! Follow the guidelines.........when you want to change your thread, you don't have to re-thread the whole thing!!! Cut the thread at the spool, leaving enough to work with.....like 8". mount new spools, tie ends of old thread to new thread, make sure the threads are in the spool holder guides right. Undo the tensions...all of them.....now pull thru the new thread. you will probably have to cut and thread the needle thread. Remember to re-do your tension!!! if you need me to verbally go thru this or anything else, you can reach me at joanbauer@verizon.net. hope this helps! Joan

If I was buying my first serger I would buy it from a dealer. They are not the easiest things to learn and you won't get any help after purchase if you buy it from an individual.
I bought my first serger, a Toyota brand, from Joanns in 1988. It is still going strong. I gave it to my daughter-in-law last year because I bought a Singer brand on Amazon for the differential feed.

go for the Bernina and if needed, the local Bernina store will give you a simple lesson on how to use it. Bernina's are the best and most reliable and need hardly any servicing.....I use mine daily for professional use and have only needed one servicing in 20+ yrs!.
The manual is quite good about settings you will need to know about and as I was first time user of a serger, I found that very helpful. I did not need a class. I still refer to my manual when working on very stretch knits, which, I rarely do. However, I have done some very decorative curly stitches on re-cycled cashmere which I referred to the manual for how-to's. Not that complicated at all!!!!