If you want to stay with Janome for familiarity, the 3160 is probably closest to what you have and is around 12.5 lbs. 60 stitches, 6 buttonholes. It's also going to have a similar look and feel with the stitch menu on the face. It's lighter than the Janome Travel Mate series. I played with one a couple of weeks ago. It's the model our local shop sells the most of for travel machines.
A step up is the 4120 and a bigger step up is the 5300, 120 and 300 stitches, respectively.