How much do you want to spend? When I was looking for a new machine I had my mother's 15-91 - all decorative stitches and buttonhole were done with a rather large attachment.... After a bit of research I decided on the Janome MC6600P. It had a larger throat, multiple stitches are programed into it (Including a few fonts). I love that I can program a variety of stitches together. When I bought it I did not want anything too fancy.
But there is a lot to be said about getting machine you can grow into. I keep my Janome up in a table for sewing but after a couple years I decided on an embroidery/sewing machine. And I got the Husqvarna/Viking Designer Topaz 20. And I love it - at times I wish I had gotten the 30 - but didn't know how much I would get into embroidery. The other part I love about the Viking - it has a large variety of stitches, it has a free arm (which none of my other machines have) and it will sew thru 6 - 8 layers of denim without skipping a beat. (My 15-91 may be able to, not sure, but the Viking can for sure.) Now I would really like the Viking Ruby - but it is not in my budget right now.
So figure out how much you want to spend and go from there.