I never made it to Mother's Rosario. I dropped it after GGO which was decent at best. Kirito has an anime harem of the loli chick, his cousin, the blacksmith chick, and Asuna.You didn't know people still liked SAO? It's one of the most popular anime today and its last arc was its best, of course people still like it. It's my second favorite anime ever due to how amazing it can be at its best. At times its not great, I hated the GGO arc but they made up for it with Mother's Rosario.
Nothing of significance ever happened between Kirito and anyone other than Asuna so I'm not sure where this idea he has a harem comes from. Sure Leafa likes him and he's flirted with Sinon once or twice but he's dating Asuna in season 2 so its not much of a harem.
Accel World was decent at times but I hated the main male character even more than I hate Kirito and thats saying something. The romance felt forced in Accel World unlike SAO and there wasn't any great friendships like Asuna and Yuuki. There wasn't any penalty for death like there was in Aincrad. To me Accel World is a poor mans SAO at best.
Him dating Asuna has nothing to do with his harem. Reference Ai Yori Aoshi if you want to see a show with a main character that has a girlfriend and the anime still has a harem. Reference Shuffle's anime if you want to see another example where there was a harem one of the girls won and the harem continued. Mahoraba is another example.
Accel World is better than SAO to me because of the main character. The guy is a fat, ugly, short, loser that fights to overcome that. Kirito is a garbage self-insert lead with virtually no personality who is perfect at everything and has all the best skills. Asuna is just about as bad she's his Edward Cullen a perfect idealized person of the opposite sex who exist only to love the main character. Their lil program daughter and fake family they had made me wanna puke.
Sure Kuroyukihime is in the same mold as Kirito and Asuna but the fact that she's in love with that crybaby loser of a main character is a far more interesting dynamic than what SAO offers. That being said I hear Kirito gets brought down drastically in the arcs of SAO that haven't been animated the romance is almost entirely removed from the focus too so it may get better. Having a main character that's the default best with no real struggle is kinda boring.