I'd say "It depends", depends on the game system, depends on the GM.
For example: I used to play RuneQuest quite a bit. On the one hand the setting is low magic (it is rare to have a lot of serious spellslingers, most of the magic is low level, not a lot of magical treasures), but on the other hand some might argue against this since nearly everyone has at least one spell. As to the "Grim n Gritty" aspect, I need only say this for the Pavis fans -- Gimpy's.
Pendragon, another game that I enjoyed, is hard to call -- the players rarely, if ever, cast spells, but the whole world is infused with magic and wonder, so it is sort of a split decision.
D&D can be converted over to LMGNG (see Gothmog's excellent thread in House Rules), but it requires massive tinkering. The base rules are very, VERY high magic and not that gritty at all. In many ways D&D defines high magic and the ease of coming back from the dead. These are aspects of the game that I attempt to tamp down in my own campaigns (start with low characters, slower advancement, very little access to cleric of high enough level to Raise Dead, etc.), but I know of some people who find this "artificial". To my mind, however, this is closer to most fantasy books that I have loved; the only ones I have found that look like D&D games are D&D novels... For all that and all that, I can still have a hugely fun time with the system, as long as I keep it in check.
GURPS is more scaleable on the amount of grit and magic, but I am not very fond of the system itself, so have played only occasionally. I have been in both High Magic and Low Magic games of GURPS, as well as No Worries and Grim N Gritty games.
The major point to all this is it all depends on the GM and the group; the system is secondary as to whether I am going to have fun or not. I can have fun in a silly campaign, in a dark campaign, in a superhero campaign, in a pulp campaign, and almost anything else; equally, I can have a terrible time in all of the above. It all depends on the mix of GM and players.