This is a tough question! I don’t really find myself wanting for the things X/GX added, when i’m playing the original. But I don’t think the original is as good a game in general.
It has a lot going for it no doubt - smooth gameplay, precise controls, interesting tracks, cool visuals and outstanding music. It’s problems are: obviously cheating AI on the harder levels, unforgiving collisions with other vehicles (which are mostly annoying backmarkers!), lack of tracks in practice, limited viability of most of the cars (Fire Stingray rules all!). It’s still fun, but that stuff tests my patience! It would have been nice if it had multiplayer as well. I think Super Mario Kart is a much better package, all things considered.
F-Zero X is almost flawless. I think i’d argue the only flaw is the low detail and minor popup/clipping issues (not the frame rate obviously!). It’s tough but fair even on Master difficulty, has a huge variety of tracks and cars, even better music. The physics - how you can truly lose grip, fly off the course, different types of drifting all make it better I think. The big selling point for me though, was the 30 cars in the race. It means there’s never a dull moment, something a load of futuristic racers fail on, since they tend to have very long courses. The vehicles can be somewhat goofy looking, but by being very distinct from each other, and attaching the driver personality, meant you could easily make them out on the track. So despite low detail visuals they made all the right choices given the hardware.
GX was like a dream come true. I’d always linked F-Zero and Daytona cause they both had that large amount of racers on the track. And it was immediately apparent that low detail wasn’t going to be a problem! Despite it’s difficulty, I think the story mode is on-point, offering events really that suit this kind of game, and feel much less “glorified level select screen” than something like Diddy Kong Racing’s adventure mode. I don’t think it’s a perfect game - the AI has some tracks where they’re much better than others. A few of the tracks are a bit long. I’m not sure i want to say the overall difficulty is a fault though. I managed to finish the entire thing, so i’ve always felt it was a bit overblown. With enough practice, you can get good enough at the tracks (and killing opponents) to beat the GP, and the story mode mostly comes down to practice with a little bit of abusing the rubber banding AI.
It IS very much a twitch based, unforgiving game though, so I can see how it might simply be beyond some people’s abilities. But to them i’d say just play it on the easier difficulties! I want to shout out the improved “side ram” controls as well. In GX, it’s on a single button and works with a feather touch on the analog stick, so you have this surgical level of precision even at full speed. X had double taps, and though some might like the additional feeling of weight that gives, it would often result in some spinouts.
I didn’t much like Maximum Velocity when I first played it. I think because I wanted my traditional locations, music and characters. But in revisiting it, I think overall it’s got a bit more going for it than the SNES game. The tracks seem a little less well designed, but there are more of them. There’s also many more cars and most of them are useable. The controls leaned heavily on the tapping to get around corners (that was in the original, but not required as much), which I think is most people’s point of contention when comparing the two. But it also has a “strafe turning” mechanic that really opens up the game to a new level of mastery. The AI is still a bit bullshit, but not as bad as the original. Over time I even grew to love all the new locales, goofy cars and music!
GP Legend is when the 2D and 3D games started to converge. 3 laps instead of 5, the boost mechanic from X, side attack, all the old characters, settings etc. I don’t know that the boost was integrated to the track design as well as it could have been, as the game ends up quite easy. It has a load of tracks although more of them are minor alterations now. It’s a fun game with a lot of content in its modes, some of it is kind of tedious though. For me, this is where i started thinking “maybe they’ve done all they can with flat tracks”.
Climax fully feels like a mini GX at times. They added the spin attack and drift types and sort of have both Mode 7 and 3D boost mechanics. It has even more tracks than GP Legend, but they consist of a lot of variants that really start to make the Mode 7 tracks seem tiresome. When you start out, they don’t seem designed for the speed of the game either, so it can be a challenge until you master the controls, memorize layouts and shortcuts etc. As a package it’s pretty loaded again (some tediousness again too), but it gets extra points for the track editor!
I went through to the GBA games just to get to Climax, since if you’re finding the SNES game doesn’t hold up against X or GX, Climax just might as it has a lot more in common.