I'm quite pleased with the 2nd gen Fire TV Stick. I have one in the kitchen/diner, and it fits nicely behind a 21 inch TV on the wall. I've had the Fire TV Stick for about a year now, and in the early days it locked up or rebooted every so often, but it's been running nicely for the last few months. I also have the now-discontinued 2nd gen Fire TV box, and it's noticeably more responsive for certain tasks, but as a media player there's not much difference, unless you need Ethernet (which I did, where that box is located).
I believe that the original Fire TV Stick (without the voice remote) was an absolute dog, but I'm only going on what I'd read in reviews/comments.
Trialed Netflix a couple of times, but the UK service left me disappointed, so now I'm either watching Amazon Prime Video, YouTube via the Smart YouTube TV app (love LGR, The 8-Bit Guy, Ashens and a few other channels) or just content from my local Emby server or MythTV DVR via Kodi. The Stick struggles a bit with live TV from MythTV in Kodi, whereas the Fire TV 2nd gen box handles it fine.
Shame that there's only minimal integration with other Amazon devices - I have a few Echos dotted around the house to control lights and stuff, and when you have multiple Echos, it's possible to ask one of them to start playing music on another one elsewhere in the house, but the same doesn't work for the Fire TV. So if I'm doing something messy in the kitchen I can happily ask the Echo to start playing music, hands-free, but if I want to start some video, I have to pick up the Fire TV remote and speak to that. Nice that the Fire TV can wake up the TV using HDMI.
Android app is good, but I tend not to use it. I don't like using my phone as a remote, in case I accidentally swipe to answer an unwanted call whilst not paying attention.