Needle up/down, needle threader, good lighting, decent harp size, adjustable needle position, thread cutter, top loading bobbin, and the most elusive in my price range is automatic tension. I thought I might want a combo sewing/embroidery machine to be able to do labels but it's not a deal breaker.
I've also been looking for stores in my area to try some machines but none carry both Brother and Janome. I did check out Times Square Sewing but they don't list machines on their website.