I'm a big fan of Synology. I am sometimes tempted to get a Qnap because they typically offer more bays and faster CPUs for the same money. But, Synology has never let me down.

Synology numbers their models by max number of bays followed by the year it's released. I have a DS414slim, DS416play, and DS420j. All have a different CPU architecture, but all get the same OS release basically at the same time with the same application support.

Last year I also added an Unraid box to my collection built from a retired HP Microserver Gen8. That's a really cool option too if you have the hardware lying around and some time to figure things out.

I would avoid a 2-bay NAS if you think you might want to expand it later. I purchased one for the office thinking I could buy the expansion unit down the road. Apparently, if the expansion unit ever loses power while the man box doesn't, it can trash the array. It sounds too chancey to me even with both units on the same UPS.