I completely disagree with controls and level design. I've always thought Sonic's level design, while good, feels more lazy because it feels alot more repetitive. It seems like it relies way too much of sending the player through loops and tubes for variation and excitement; Mario's levels have more actual variety (I can give you some examples if you like). Mario also has far more enemy variety. The robots in Sonic are pretty repetitive and lazy. I also think the controls in Sonic feel more touchy.
Atmosphere is a very subjective measure that I'd probably agree with you on. Music I absolutely agree with it, but I don't feel that's particularly pertinent to quality.
Also, getting keys is not an optional thing in Mario and for the bulk of stages, you simply get to the end, so I'm not sure what you mean with the bolded.
I don't think they're lazy, they're different styles. Mario World stages are more about messing around, and Sonic's are quick and to the point. I like the latter.
Control, isn't even a question to me. It's the momentum based gameplay that allows the player to do things like this. No other platformer makes me feel in control like Sonic, while Mario feels very run of the mill.
I like my platformers to be straightforward and not have any filler. In Mario World, you do need to find keys, figure out the right path, and in one particular level there is a sign that flat out tells you to either get a certain amount of coins or beat it as fast as you can to beat the game. I find all of this to be nonsense. The reason Super Mario Bros. for the NES is my favorite of the series is because it doesn't consist of so much BS and time wasters.
You may be able to mess around more in Mario World stages, but I don't think they are about that all. Like Sonic, they are about getting to the end. The difference is that the developers throw a wider variety of obstacles at the player in Mario. I'm not knocking Sonic for having a different playstyle. That's fine. But I do feel that the Sonic level designers were not nearly as creative. And while the levels in Sonic are well-designed, they seem to use the same tricks alot.
About control: Sonic's control might be faster and more momentum-based, but that doesn't make it more "quality". Also, I'd disagree that one feels more in control with Sonic. I feel that Sonic is the one that often takes control away, even if it's for short periods, from the player while Mario doesn't.
Furthermore, you call Mario's controls run of the mill, but it only seems that way because more platformers copied Mario's style. I don't think it makes sense to call the pioneer run of the mill.
I do admit that I could be remembering wrong about the keys and what not. It's been a while since I played Mario World.
I disagree. In World they give you a big stage , too many powerups, and want you to go looking for secrets. Super Mario Bros. didn't do this. It was one powerup and go right, which I think is the better formula. Lacking creativity? Mario uses the same tropes over and over again with the same music playing. Sorry, I don't know how you can say Sonic's levels lack imagination with zones like springyard, scrap brain, starlight, chemical plant, casino night, metropolis, hydrocity, marble garden, ice cap, launch base, lava reef, and death egg. Again their playstyles are different, and so I think you are knocking Sonic's levels for that.
What? If I feel like I can move and handle better with the momentum based gameplay, how is that not pertaining to the level of quality? I feel like I can do anything with Sonic, and I don't get that with Mario.
I call it run of the mill, beause that's what it is. It's not distinctive. One of the reasons new 2D Sonic games get so heavily criticized is because they don't control the same as the classics. Nobody cares that New Super Mario Bros. gameplay is different from the classics because the gameplay and controls was never the standout defining attribute. If other games tried copying Sonic's gameplay, they'd be exposed for being ripoffs, which happened quite a lot back in the day.
I beat Mario World again like a month ago, so it's relativley fresh in my mind. Personally, playing Sonic and Mario back to back really exposes Super Mario World as being the most overrated game of all time IMO. Now after saying all that, I still like the game, but I think Sonic is leagues better.