There are several problems with the harem genre, particularly in the original form, that make it definitely not one of my favourites.
As I've noted elsewhere the proliferation of characters in Ranma 1/2 is one of the reasons I gave up on Ranma after the first season (and often the first 10 episodes).
Tenchi Muyo has a number of issues, starting with Mihoshi's existence at all and moving on to the "ewww" factor that is Sasami.
El Hazard doesn't really qualify. There is considerably more balance in the cast, more than one romance happening, and whatever else can be said for Makoto, he made his mind up soon enough.
I haven't seen Love Hina but from the sounds of it I liked it better when it was Maison Ikkoku. Sorry, I couldn't resist the cheap shot. :) Maison Ikkoku is really too focussed on the main relationship to really qualify as a harem anime anyway.
In short: the harem anime isn't a genre that I'm terribly fond of.
So, inevitably, I'm going to pick a gender-flipped parody: Ouran High School Host Club.
I don't want to spoil it too badly so I'll note that it's locally available and good fun.
Just remember that Ouran is a parody... :)
Day 1 - Very first animé: Robotech, Gall Force, Vampire Princess Miyu.
Day 2 - Favourite TV series: Card Captor Sakura.
Day 3 - Your animé crush: Oh grow UP already.
Day 4 - Favourite Film: My Neighbour Totoro.
Day 5 - Animé character you feel you are most like (or wish you were): Kinoshita, Rocket Girls.
Day 6 - Most annoying animé character: Lynn Minmei, Super Dimensional Fortress Macross.
Day 7 - Character you’d most like to slap: Hiyama Hikaru, Kimagure Orange Road.
Day 8 - Most epic scene ever: Launch day - Wings of Honneamise.
Day 9 - Saddest animé scene: The passing of the Fortune Twins - Nariya and Eriya.
Day 10 - Favourite slice of life animé: ARIA.
Day 11 - Favourite mecha series: Patlabor: The Mobile Police.
Day 12 - Best instalment of a franchise you don’t like: Mobile Suit Gundam 0080: The War In The Pocket.
Day 13 - Worst instalment of a franchise you do like: WXIII: Patlabor the Movie 3.
Day 14 - Current (or most recent) animé wallpaper: I think I had a Silent Mobius wallpaper once.
Day 15 - A reality check for a genre you like: Romantic/Heroic Space Pirates.
Day 16 - An animé classic that simply doesn’t work for you: Ghost in the Shell (film).
Day 17 - Best Background Music: Silent Mobius 2: The Motion Picture.
Day 18 - Best Five-team: Silent Mobius.
Day 19 - Change you’d like to make to any one animé: Add an animation budget to Lodoss Wars.
Day 20 - Most ambiguous animé character: Reki, Haibane Renmei.
Day 21 – Favourite OAV Series: El Hazard the Magnificent World.
Day 22 - Animation studio you'd most like to slap: Gainax.
Day 23 - Animé you think had the best, or most intriguing art: Reki's paintings in Haibane Renmei.
Day 24 - Favourite animé hero or heroine: Hitomi Kanzaki, Vision of Escaflowne
Day 25 - Best animé villain: Nakago, Fushigi Yugi
Day 26 - Your favourite harem animé: Ouran High Host Club
Day 27 - Favourite animé opening theme song
Day 28 - Favourite animé companion/summoned creature
Day 29 - Best Animé Music Video
Day 30 - Favourite animé ending theme