Well here is my opinion.

The original Metroid has not aged very well, it is extremely frustrating, VERY unforgiving, no map,no sense of where to go, absolutely nothing. On top of that you have that long password to put in every time you want to go through. The first 10 minutes are the hardest as the game gets easier once you get the long beam so your beam doesn't end 3 feet in front of you. I beat it, and it took me a long time to draw out the map and everything. You can go find a map of the full zone online somewhere but then yhou might as well not play it.

As for whether or not to play Metroid Prime or Super Metroid first, I think you would appreciate Metroid Prime more after playing Super Metroid. Super Metroid is to Metroid what Zelda Alttp was to the original, a Massive improvement, you will not get frustrated, there IS a map, it has aged very well. Some music returns, some bosses return, a lot of the items. However if you play Super Metroid after Prime, I think you will have a similar experience. Whatever you do DO NOT skip Super Metroid because you had a bad experience with the original.

I figured Super Metroid would be better. I plan on playing it after Other M because thats where it is in the timeline...i think.

I don't really get Nintendo's way of making games.
They keep making games from the Mario, Zelda or metroid Franchise.
Why can't they just try out many games like the PS3?

Sony has their own 1st party titles that they draw on. Just not as many and not as big. PS3 relies heavily on 3rd party support (IMO) whereas Nintendo and 360 are more self sufficient.

They.... they do.

The Excite series, Pokemon, Animal Crossing, Donkey Kong, Pikmin, Sin and Punishment, Endless Ocean, Fire Emblem, Kirby, 1080, Starfox, Wave Race, F-Zero, etc. All published by Nintendo.