I own a pfaff tiptronic 2020 and a bernina. I love the bernina for quilting because of the stitch regulator but I do my best piecing on the pfaff!
I'd been quilting for a few years when I bought the bernina. I couldn't understand why my blocks weren't turning out as nice as usual until I realized I was used to the IDT on the pfaff. I immediately went back to the pfaff and had no more difficulties with corners matching! The IDT certainly pays for itself, as far as I'm concerned!
My sister just bought a basic pfaff and she loves it. I'm not sure if you can go wrong with any of the pfaffs.
Best advice is to go try them out and look at the bells and whistles and stop looking when they start to get out of your price range.