I admit, I like the smut in a harem, but the heartwarming light-toned romance in a non-smut harem story also has its charm.
However, if it's come to make a choice ... I'd choose those with smut.
One of the harem stories without smut that I truly enjoy is Sononochi and Kujibiku Musou.
As for those with smut, well ..., let's go with Shura Wrath by Mars Gravity, the MCs by that author born with gotta catch 'em all mindset. Ah, Summoning the Holy Sword is also a good harem with some smut, though, I personally disliked the MC.
It's a different story for reverse-harem, ain't touch any of them. But we're talking about the normal general description of a harem right?