1. Super Metroid (I first played this on Wii Virtual console of all things even though my older siblings owned it on SNES)
2. Metroid: Zero Mission (imo vastly superior to Fusion)
(Metroid Prime 3: Corruption)
3. Metroid: Samus Returns
4. Metroid Fusion (my first Metroid game, I kind of think that's the case for a lot of the other people voting for it over Zero Mission or Super)
(Metroid Prime 2: Echoes)
(Metroid Prime Hunters)
6. Metroid II: Return of Samus
I am a pretty big Metroid fan. I also have not bought a switch yet, but Metroid Dread will probably do it. I even used to have a youtube channel where I made short gaming clips before it was deleted in 2011. My own personal Dread discussion video on youtube had ~100k views at the time (can't prove unfortunately, but it was actually a primitive video with windows movie maker) and another 10-15k on game trailers (I found years ago by googling my youtube username but I did not actually upload it there and also can't prove because the site doesn't exist anymore?). I actually think I had the most viewed video on the topic at the time and it was just me anticipating Metroid Dread from the Metroid Prime 3 Easter egg (which I guess I was correct in the long term lol - I thought it was coming a lot sooner obviously). I feel pretty much equal about how much I care about 2D vs 3D Metroid overall. I thought Metroid Prime 4 would be the reason I buy a switch because I did not see this coming.
The only Metroid game I haven't played is Federation Force. It just never appealed to me and character models looked goofy graphically compared to Metroid Prime Hunters. I definitely think Super Metroid deserves its "one of the best games of all time" spot. I really hold all of them in high regard except Metroid II. It was the only time I was disappointed in a Metroid game.