I worked through college selling pcs and the like. I ultimately preferred Epson for photo printing and scanning. I owned one of their all-in-ones and it worked flawlessly. Now HP has the bigger name but Epson primarily does printers and scanners, it is their core business.
Their printing method prints out to the edges of the photo meaning you don't need to use perforated paper. Their paper is also water proof not that that really matters but should relate to the overall age of the photo to be increased.
I never sold lexmark, since they were notorious of having cheap printers and quarter/half full cartridges. Epson always gave you full ink cartridges right out of the box. HP and lexmark like to package only the color ink cartridge in new printer boxes meaning that you either need to buy a black ink or when you print your color cartridge will need to apply the appropriate colors (usually all of them) to represent black on your paper, accelerating its ink usage.
All and all, the last nail in the coffin even though it fully doesn't matter for new printer purchases. I have an all-in-one epson inkjet, an epson scanner, and an epson printer as well as an HP Laserjet 3330 printer/scanner/fax/copier.
Every epson product had vista driver support immediately. The HP laserjet's scanner has no driver support at all for Vista however the printer works. This type of customer service forces the customer to purchase new hardware which would be a seemingly trivial effort on hp's part to release the updated vista driver.
HP does make very sweet laserjets though. My Laserjet 4+ lasted 10 years. I can fix it with a $5.00 part but I don't have the motivation since the 3330 prints so well.
Go to a Brick and Mortar with a 4x6 photo of yours and a memory card with some pictures on it. Go on a slow day and have one of the representatives use the different all-in-ones to
1. Scan and recreate (copy) your 4x6 photo
2. Print a photo off of your memory card
Use the same 4x6 and same memory card photo and write on the backs of the photo's which printer printed it and use that for your research.