I have a Viking Sapphire 870. Would not buy it again. When it sews well, it sews well. When it doesn't it doesn't - always a little persnickity. Right now it is in the shop - third time in three years. This time simply refused to FMQ. Thread breaking every few stitches. Have had problems with the automatic cutter - so I don't use it except when in the middle of the quilt. Thread kept coming off the take-up lever, had a part put on that which stops it most of the time. Less than average thread on the bobbin so refill a lot. And sometimes makes funny sounds and just doesn't want to sew, or it will sew poorly.
I am using my 40 year old Kenmore which, relatively speaking is a workhorse and a dream. The harp is small so quilting a large quilt is hard. Also, no feet for free motion quilting (or much else, just basic feet) - use a regular foot so visibility is difficult. However, the quality and ease of the FMQ is better than the Viking. Also, in 40 years it has never needed any servicing. I can open the thing up and clean it - with a few drops of oil it is like new.
If I could just get some newer feet for it, I think I would make it my number one machine, even when my Viking is out of the shop.