First off, I don't really like the notion of CE vs SE, but I'll do my best to ignore that from here on out.
"It Depends." By which I mean it depends on your goal (since you said "better" not "faster").
Cottaging is going to be faster everytime if the cottages are already villages/towns. A grassland Town will produce as much or more culture than an artist, even with the sistine chapel boosting the artist, as long as your cultural slider is set to 100% (remember that by swtiching to free speech for +100% culture, you also get +2 commerce from towns from said free speech, which means the town is producing a minimum of 6 commerce, without financial, printing press or river bonuses). And it won't cost food, as it'll supply enough food to cover itself. But if you artist up all your 3 cultural cities, you can try and do it that way instead and not have to devote anything from the slider at all (though even an all-farm-and-artist city produces some commerce, through Trade routes, so not setting the culture to 100% will still be slowing down your victory). But theoretically you could try to keep researching rather than simply "shutting off" all research, which is the norm (as it is faster). If continuing research to stay somewhat competitive while you culture up is your goal, then using Artists, Representation (if you have the Pyramids) and setting the research slider to whatever you can afford is the way to go (note though that this is very much a slower- but-possibly-more-sure-depending-on-circumstances victory goal. It could also be that this decision bites you in the ass though, as perhaps someone outstrips your research and invades you anyway, and if you had simply focused on culture you might have already won before said invasion!)
Even a cottage-based cultural victory should use an artist or two, in lieu of any non-commerce tiles (ie if you have a couple of grassland mines in your culture city borders, you may as well just stop using them and convert them to artists). Any fresh cottages will also simply be producing too little commmerce and should be switched to artists if speed is all your concerned with.
So in general, "CE" and set culture to 100%, and change any mines or just-made-cottages to artists, as that is the fastest, but if you think that acquiring a few more techs would make your empire much safer during your "cultural-boom" then that's the way to go. But the latter is not usually correct.
The main thing about artists and cultural victories is spawning Great Artists, though, and you're going to need some artists for that
EDIT: How did I forget Building culture? Lol. But remember that building culture directly produces culture that is NOT multiplied by free speech and cathedrals, so Town and 100% slider > production of culture directly, so Town over mine for sure, and Artist > mine