Graphically, the SMS is so far ahead of the NES it's not even worth to mention really. Just compare Ghostbusters, Shinobi or any other game that got released on both platforms. Look at SMS games like Aleste, Sonic 1, Land of Illusion, Lucky Dime Caper (nearly looks like a early Mega Drive game), Phantasy Star (the FPS 3D dungeons especially) and it should be obvious that graphically the console was miles ahead and the SMS didn't suffer from the insane flicker (compare Double Dragon) or the garbage pixels on the edges of the screen (just look at Nintendo World Cup) which plague the NES
your forgetting late releases like kirby or stuff like the megaman games, mario bros 3. look better than pretty much any master system games.
also if we want comparisons Castlevania 3 blasts master of darkness out of the water in terms of visuals. the latter looks mega boring in comparison
just cause the master system supposedly has better grapics doesn't mean that the developers actually made full usage of it. very few games that got to look as good as phantasy star, fantasy zone. overall Nes unironicly has better looking games.
Sure some ports look better on master system as it should but many of those games are not notable and that's while one ignores the actual nes staples. Nes has much better looking games since way more developers worked on it and tried to push the system to it's limits and way past it's lifetime.
Technically the master system developed games for way longer with tectoy but I don't think it counts since ports of street fighter II didn't look that good. I don't think the same quality of devs stayed behind to develop stuff in those ultra late era's for master system.
also if we want to make a closer comparison the Ninja gaiden games. The nes version has better details and while the master system version has more color and clear objects it looks very simplistic in comparison. I'd favor the nes looks on that one let alone the later entries which look even better. also The nes version of Ninja gaiden has one of the best 8 bit pixel cut scenes of all time animated. Master system one has boring still images as the cherry on top. Developers put way more effort in the weaker Nes console which made better looking games as a result or in some cases insanely better looking games like kirby/ megaman.
I'll take extremely late nes era grapics over early megadrive. Have you seen stuff like sword master with snes grapics, on top of having good sound since it's nes. lucky dime caper lookes kinda primitive in comparison. let alone stuff like mr gimmick little samson. I'll take those visuals over anything master system ez. unlike master system which is very simplistic static looking with even it's best looking games, it's animated greatly with plenty of details over here in Nes land.
In Europe the Master System outsold the NES 5 to 1 or so, it was far ahead in the UK, Spain, France, Italy and Germany (altough Ariolasoft dropped the ball there initially, then again, Nintendo Europe did a way worse job to the point that SMB3 came out after SMW for the SNES was already on the market)
I don't think european console sales count prior to snes because they where absolutely pitifull. It was all about amiga, commodore pc esk sales over here. consoles where not popular at all. Hence why I wouldn't really consider it that big of a victory or mentioned it while making said quote
considering the Nes sold over 60M and the master system just a palty 13M The Nes murdered it.
edit:
So after looking stuff up, the Nes sold over 8M units in europe while the Master system sold over 6M. so in europe the nes outsold the master system.
You are correct however that in the UK the master system was far more popular but overall the master system took an L in europe. although it pales in comparison to how poorly it did in the states.
but sound was never the strong suit of Sega, despite having some great composers like Yuzo Koshiro or Tokuhiko Uwabo on board.
sure master system had garbage sound, just saying that fm sounds didn't kill my ears so that's a plus over them originals it was very basic/ bland at the end of the day but I'll take that over the ear greating high sounds that the master system loved to use anyday.
That being said sega pretty godly with sound in 16 bit era and afterwards. Music is great favor sega in terms of ost/music overall compared to snes which is mainly just trying to emulate realistic instruments/ sound effects. I favor the more arcade/ videogame esk music sega went for. More my kinda style in what I want in a retro game far more interesting.
Now if where talking sound effects sure, exceptions aside wasn't their strongest point although quite a bunch of games exist in which you don't notice the limitations.