FWIW, here's what I'm using:
4 x HDD enclosure. It's fine. Nothing to rave about, but it gets the job done and has done so for many years. I run it strictly JBOD over e-SATA. For my purposes, the included controller card acts purely as port multiplier -- I do my own daily redundancy data management with FreeFileSync. (I simply don't trust low- or even mid-market RAID controllers...though honestly I've felt that way for 10+ years and things may be different, now.)
HDD enclosure. I use this with a BIG HDD for my off-site backup of critical data. Also connected via e-SATA. If and when I need to bump up to 2 x HDDs for off-site backup, I'll probably just get another one of these instead of a 2-bay enclosure. Great ventilation, and the e-sata is plenty fast.