Based on the available reviews on-line, quilters love the Juki. For me, it has a nice combination of features: the feed dogs drop, and it has the up/down needle switch, speed control, knee lever, an automatic thread trimmer, an extended sewing bed, and the right accessories. The Juki also seems made for easy maintenance, with regular oiling and good access for the removal of dust bunnies, so I hope I won't need to take it to the shop for cleaning as often as my current machine.
My other option would be to stick with Janome, but I've seen complaints about the 1600P, Janome's straight-stitch machine. The feed dogs on the 1600P don't drop, and there have been reports about thread knotting up or breaking. Quilters seem to adore the Janome 6600, but it's beyond what I'd like to pay and has a lot more bells and whistles than I need. Plus, I hate to buy a machine with tons of fancy stitches but no free arm. But the AcuFeed feed dog system sounds wonderful and earns rave reviews--very tempting. The 6300 might be a good compromise, except it doesn't have the AcuFeed system, which seems to defeat the purpose of moving up from the old 5000.
What to do? I suppose if someone wants to give me around $5000, I can go buy the HandiQuilter Sweet Sixteen! (DH, are you out there?) But barring that, I'm going to check out the Juki sometime in the next few weeks. In the meantime, Happy New Year!