What we're using is a 8850CDW, which is a bit higher end than many people need. We have a 8810DW (which is B&W only) and the 8850CDW. Both of these units have document  feeders, and they will do double-sided copying/printing/scanning. We have a ton of paperwork in our household, so when I need to scan/copy/fax/etc, I don't want to feed documents individually to the unit, I want to be able to lay 50 pages at a time into a document feeder and then go do something else.

We purchased both of these units at Costco some years back.

From what I see on Brother's web site, this appears to be the closest new equivalent:

https://www.brother-usa.com/products/mfcl3750cdw