Excarius said:Freezing - Has 2 seasons, features harem type IF im not wrong, has comedy with ecchi. From what i see on your list, you seem to like ecchi as well so those series i recommend will and can have ecchi scenes. This one do have ecchi as well, and there is eventually a female MC tsundere girl (there is both male & female MC's). It has comedy also! As always, he chooses one out of his harem :)
Asu no Yoichi! - If you want more comedy with better harem with alot of character personalitys such as dandere, tsundere etc, then watch this! All girls do have different type of personality. And there is a definitely progressive romance going on that is interesting with tons of comedy presented, however there are not much to care slightly of ecchi alike scenes although i don't remember if there were any skin shown but if not, there is accidents going on, i reffer as Fanservice :P also male MC is strong. As always, he chooses one out of his harem :)
Campione! - Male MC is strong, there is ecchi, harem, superpower. Harem is not very strong here but you will definitely get the vibe of harem, and yes he chooses one girl ofcourse. There is romance.
Date A Live - Male MC is not strong really, there is harem definitely and the season 2 is way better where they get along with his lover that he did choose among other girls. There is no ecchi if im not wrong, a good hearthwarming relationship is also going on. Harem is also going on too, and if you like tsundere type female (like in the Zero no Tsukaima the Louise), then no doubt, you will enjoy this anime more then.
Ichiban Ushiro no Daimaou - I don't know if i should call this harem, however there are girls around him, but he chooses one girl, and the girl is eventually a tsundere-type girl. Romance is well developed, male MC is a overpowered beast, i highly recommend you this, it might not 100% fullfill your criteria, but you should watch this. You are new to anime, soon or later, you will end up watching this sooner or later, and will rate high if im not wrong.
Nisekoi - This is perfect one for you. It's a normal school life type of anime with lots of comedy, harem and romance. There is even tsundere type of girl presented, if im not wrong there is 2. Im reading manga and so far didnt watched season 2 of this, however it's adaptation of manga and manga & anime first season went same, so no doubt season 2 is good too, all i can say is watch this, but manga is still going on and im on chapter ~150 and so far there is no really chosen girl, maaan just really watch this it is good, the season 1 ends good but season 2 exists and since it's adapted from manga, i believe season 1 ending is not what it ends like. Long story short, i watched only season 1 and if i judge the season 1, it fits very well to your criteria, that said i have no clue how season 2 will go.
Rosario to Vampire - Harem, ecchi, comedy, romance, supernatural. Watch this, definitely worth, i dont want to speak more about this anime, just watch thats it.
Infinite Stratos - Harem anime, with comedy romance, i dont remember much but this is absolutely your taste. I dont remember ending very well because i watched it in 2013, but it goes exactly as you want, and ending might NOT end up with one girl, i cant remember, that said you will enjoy this anime there is 2 seasons of it. Female MC (there is male MC as well, it revolves around male MC mostly) is tsundere type, and there is definitely harem in it.
Ore no Imouto ga Konnani Kawaii Wake ga Nai. - Not really harem or romance, but it was good, it's something different and i want you to try this. It is slightly harem (there is 2 girls) and romance too, well first season might not give that vibe really to you, but season 2 gives absolutely. Don't expect very well made romance as it's focusing not just romance but many other parts such as Comedy and the character development. Try this, 2 episode or 3, if possible 4 or 5 to determine if it's your taste. End of the season 2 i cant remember how it ends, if i don't remember wrong, it ends with choosing one girl. Either his little sister or another girl, but hey, i don't want to spoil and neither want you to think bad about this anime, it is brother & sister, sure, but it's not dirty as you might think of, that's why i want you to try this.
Seiken Tsukai no World Break - MAle MC powerful, starts as weakling but each episode he gets stronger, there is harem and comedy. Romance is very nice but mild, this one has a different romance style, in another words it is a definitely nice anime and fits very well to your criteria. Harem is really a harem, and he chooses only one girl. Although there IS a reason why he chooses that girl, you will understand why when you watch it. I liked it alot, ending is not bad, it's good so don't be worried with bad ending.
Sekirei - Can't remember, all i remember is male MC is harem, he gets tons of girls and if im not wrong he is choosing one girl. Really, i cant remember, watched in 2013 when i was new to anime like you, i gave it at that time 10/10 but as i discovered new anime and genres & combinations, overall score of it got lowered, that said since you're still new, there is no doubt you will love it, give it a try. Romance is problem here because i don't remember how it is, neither do i remember how it ends, but it's a REAL HAREM ANIME, that's all i can say, it has comedy.
Astarotte no Omocha - Known as Zero no Tsukaima's clone. If you liked Zero no Tsukaima, you can watch this as it's known to be clone of it, it won't give same vibe and lacks the deep relationship which in Zero no Tsukaima there was.
All these anime are perfect for you, i remember days where i was like you and posted countless threads to request harem, comedy, superpower, fanservice, ecchi etc etc genres, everyday i was making research and watched only the best ones, so from those experience, i picked those best ones for you, i hope you enjoy them, please try ALL of them, im pretty sure you should like them all.