Kaichou wa Maid-sama!, Himitsu no Ai-chan Recommendations
There's a love story that begins as a rivalry on the side of the girl. both involve maid :D
both girls fight or deny their sentiments, and are strong willed.
Kaichou wa maid-sama is better imho, because the story of himitsu no ai chan seems to have evolved from a one volume story to a serialization, so the first chapters are too quick and go over a lot of things that could have been better thought out a little slower for a few extra chapters :).
both have tough girls with a rival that all the girls like yet they cant figure out why
both working at a maid cafe when there rivals work in and trouble ensues
Basically the same idea.
-Double Harem in Himitsu no Ai-Chan (basically all the girls like Reo) and (Reo,Takumi likes Ai)
-Double Harem in Kaichou wa Maid-sama! (Basically all the girls likes Usi) and (Usi,and Hinata likes Misaki)
-Both female leads are working as Maids in secret (although both have different reasons)
-Basically both lead females are tomboy-ish and most of the girls in school like/love them
-Usi and Takumi are part of the cooking staff for the maid cafe
-Both female leads are kind of...erm..dense
-Both female leads have black hair
-Both mangas have strong female leads.
-Both heroines have a part-time job that involves cosplay or a "secret life"
-Both male leads are popular and handsome
-Both males don't have any interest with girls except the heroine
Overall, they're both great mangas!!!!!!!!