i have the 98Q but i wouldn't use it for piecing so in this case i would go with the Pfaff.
the 98Q is a straight stitch only machine so if you ever want to do machine applique you'd be out of luck.
if you like Juki you might want to look into the F series either the 300, 400, or 600.
i have the juki f600 and i love it for piecing. its a 9 inch throat so its great for table top quilting.
i have the juki 98Q on a frame and use it strictly for frame quilting.