The flashlight I enjoyed the most in 2017 was the hi-CRI HDS clickie that I bought in 2010. It is still, after all this time, my favorite light. It's the only reason I keep RCR and CR123 batteries around, but I don't hold that against it.
However, since this thread is probably more interested in newer flashlights, the new flashlight I'm most excited about is the Eveready 1D that is currently selling for about $3 each just about everywhere. It's either the 3rd or 4th generation 1D flashlight from Eveready and this time they got it right. The beam is nice and useful (uses a reflector rather than an optic, thank god), the tint is acceptable, the switch works well and seems robust enough, and most importantly, I've been getting useful light (around 1L or so) out of batteries that are so dead that my battery tester won't recognize them anymore. I finally have a light that I can feed the half used C and D cells that seem to accumulate as well as the AA and AAA "heavy duty" batteries that come in TV remotes and such that I'm terrified to use in anything I actually care about.
Seriously, at $3 and capable of getting 100's of hours of useable light out of a D cell, I think the newest Eveready 1D is a real game changer when it comes to the lights we stash around the house and car in case of emergency. It also makes a great night light if you put a "dead" battery in it.
Honorable mention goes to the Manker E02 for being a relatively inexpensive but tremendously useful light. I've attached it to my cell phone holster so I always have a hands-free light source when I'm outside in the dark messing with my keys. It is my backup-backup-edc (I edc the HDS, my backup for it is a Rayus C01, and the Rayus' backup is the Manker). I've always had a weakness for angle head flashlights.
I'm looking forward to receiving a Malkoff MDC AA in the next couple of weeks. Hopefully it'll make the list for 2018.
--flatline