Indeed there is no absolute truth to be found in that matter. But there are still the facts that we can get by analysing the games, if one cares to do so, and also the fact that a lot of people enjoy playing them. It also makes for a much more interesting conversation rather than just dismissing everything as personal opinions. 

I mean I never denied that a lot of people enjoy playing them.

The multiple paths design didn't do it for me cos the game seemed at odds with itself; encouraging breakneck speed where input was minimal, but then slowing things to a halt for awkward platforming that didn't control that well.

The games are not intended to be fast when first played. The player is expected to take it slow, explore and master the physics. Here is a speedrun of Sonic 2 which demonstrates how fast one can go if they have total mastery of the mechanics and the level design. Keep in mind that the multitude of paths add to the variety of different ways one can approach their runs of the level. "Which is the fastest way?" "Most people choose this way, but what if there was a way to make it to the end quicker using another path?" These choices give depth and replayability. Later games like Sonic 3 and CD add secrets and collectibles which offer another type of challenge to the players that just want to explore the beautiful levels. 

https://youtu.be/D6yZxuDFGG0?si=rHzS7plOdpTSTULm

I get what they were going for, I just find that the stop-start nature of it and the platforming controls when moving slowly don't feel good.

I've been playing Sonic since I was 7-8 years old and his controls are very natural to me so I can't relate. I have heard other people saying that they can't get used to them though. 

Yeah that's probably the thing, I first played it when I was 19 in 2008, once I left home and could buy the consoles I missed out on as a kid like the Megadrive, Gamecube, etc. 

I have to keep reminding myself that you're only 22 years old! That like it's actually possible for someone alive today to have never played the original Sonic classics before. Wow.

Anyway, that's a great perspective on what the original Sonic the Hedgehog at least sought to accomplish! When it first came out, my preference was for Sonic the Hedgehog by a landslide. It was bright, colorful, faster-moving, had a way hipper soundtrack, and was just generally more stylish. All the things that said cooler and higher-end, which is what many of us who'd grown into our tweens on the NES were looking for. In 2025 though it does seem less truly novel to me. I don't know if I totally agree with the notion that Sonic 1 succeeded at that goal of speeding you along to your last Game Over point, considering the existence of like the Marble Zone, and the goddamn Labyrinth Zone that inexcusably gets a de fact fourth act in contrast to all the others, etc., but that is very much a byproduct of taking too many design cues from the Super Mario franchise. There are just too many things there to slow you down. Sonic 2 is where the hedgehog really found his footing, to me, and became truly his own thing. Not so much clutter yet plenty of challenge left over, plus streamlining the zones into (generally) two-act affairs gives the whole experience a much greater sense of momentum. Even its water zone (Aquatic Ruin) is vastly superior for offering skilled players a totally above-water route, with going underwater serving as a de facto punishment for screwing up and an incentive to master it.

Mario wins because the platforming is far tighter.

Sonic's selling point is speed, and so much of the Sonic series is prohbitive to speed, starting with the Marble Zone, the very second act of the first game. In terms of the actual platforming, Sonic simply isn't as good. Meanwhile, there are parts of Mario and Donkey Kong Country that can actually get pretty fast, but they are only in limited circumstances, and the games are designed around those segments, instead of the games being designed around raw speed, which falls apart the second you have to do anything other than run. I liked Sonic's sound and visual design, but it still had nothing on what the best of the SNES had to offer. 

I have been gaming since 1981, so I cut my teeth on Super Mario Bros, which was in itself an adjustment for me from Donkey Kong and the original Mario Bros arcade game. In the former, Mario couldn't survive a fall of any depth, and in the latter, though Mario's jumping and falling abilities were improved, you couldn't jump on the enemies.  

It also didn't help Sonic that by his first game came out sandwiched between two all-time Mario classics, SMB 3 (which pushed the NES beyond what many thought was possible) and SMW (where Nintendo really took advantage of the SNES's increased horsepower to refine that formula still further). 

The 16-Bit Sonics are not "fast"; that's the modern series ever since Dreamcast, where it just became a straight line and holy shit speeeed!

The original 3 games have branching paths in most levels. The goal was to maintain momentum. Avoid obstacles and stomp enemies in stride, and do it long enough rewarded with speed.

I played both of these games when they were brand new.  My reaction to SMB was so much more blown away than I was compared to Sonic 1, and I have spent a lot more time playing SMB 1 back in the 80's than I ever did with Sonic 1.

Which do I prefer to play today?  Sonic.  Sonic 1 grew on me over time.  I had to get past the water level.  Once I did that I recognized Sonic 1 for the masterpiece that it really is.  On the other hand SMB has been completely overshadowed by SMB3, while Sonic 1 is still my favorite Sonic game.  So I don't go back to Mario 1 very often, but I would really like for them to bring back SMB 35.

Anyway, I think Sonic 1 has aged better, and I still like going back to play again even in recent years.