I have the Sapphire 835 and I love it. I can't compare it to any other machines though since my last one was a 20 year old Singer that I got new... 20 years ago.
I don't quilt with it, just piecing really, and it's great for what I use it for. I like the needle threader and the 1/4" setting. My piecing has really improved since I got it a couple of years ago.