I like my Bernina QE 440. It's intuitive, sews beautifully. It's heavy to carry to classes but I manage that ok as I have a Tutto rollable bag with steerable wheels.
I also have a small Brother 6000i that is very portable and good for classes where I'm mostly doing straight stitching. It was inexpensive. Only downside was I had to take it in for servicing because it requires a 90/14 needle if using invisible thread, embroidery threads or 40/2 ply threads. With the 90/14 needle it sews anything and everything.
I have a Viking Designer 2 that I hate (have had it 6 years) so I replaced it with the Bernina.