My entrance to Metroid was with Prime 1 and 2 a few years after launch. Then I played the 2D games - First Zero Mission, then AM2R, then Super and finally Fusion, wasn't into og M1 and certainly not og M2 and I tried Samus Returns on 3DS but didn't like it so went with AM2R as my M2 equivalent, which was amazing) - all in a row, back to back in 2021. I played Dread on release and loved it.
I still adore Metroid Prime 1 (MP2 beats it out in so many ways for me but probably still give crown to MP1 by the tiniest of margins) and its my favourite but ZM, AM2R and Super are all god tier games also and I wouldn't say they are worse than MP1/2, can't compare them. Fusion I also really really like and totally love parts of it but the linearity is annoying for me, I love to go back in Metroid at any moment, you can only do that right at the end in Fusion and even then you need to find the elevator skipping shortcuts for some of it I believe (it would've been too annoying without a few hints from walkthrough).
All of them have weaknesses to me, ZM was too hard to 100%, some of the shinesparking required was too much for me, in AM2R, Super, Fusion and Dread I never felt like the tasks were annoying, I knew what I had to do and it was tricky sometimes but the difficulty came more in working it out than actually performing the inputs. Except maybe that Super shinespark + ball spark one where you can to run in from offscreen and stop within very few frames of time and then do several sparks in a row lol.