Super Mario All-Stars for the SNES to me is the definitive way to play the original NES classics. For today’s gamers who’ve been exposed to constant remakes of today, remakes even happened back then, they just weren’t a regular thing. This is one example of them and Nintendo hit it out of the park with this. The visuals are crisp, you would almost not believe that it was originally released back in the early 1990s before its re-release later in 2020. Just everything about this package of games, is the gold standard of what remakes should be about.
Super Castlevania IV is another example and yet another game I put in high praise as a remake. This entry of the series, though confusing at first, is the re-telling of the very first Castlevania game released. They just wanted to do it on newer hardware at the time and do things they couldn’t with 8-bit constraints. That really showed here because everything about this game is nothing short but amazing of a remake from visuals to music to even the additions that might’ve not been possible the first round.
Both of these examples are a testament to their craft because to this day, nobody is touching them to remake them from the ground up. They may get repackaged, but it isn’t like anybody looks at them with the thought of an entire do-over.
SMB1 (and by extension 2J) has a physics bug with hitting bricks, and a patch exists to correct this, but to my knowledge 2 and 3 play identically.
Even putting aside this though, SMB1 feels wrong to me without its original sprites. I actually like the SNES version of SMB3 though.
I had the exact same comment (your second paragraph), which I deleted because my comment got too long. I think the original Super Mario Bros on NES is the way to play it and I disklike the All-Stars graphics. But I really like AllStars-SMB3, because the glitchy graphics on the side is resolved and most importantly the battery save. The upgraded graphics fit the game well too. I stand by this opinion since the early 1993!