Raze wrote...
Ichigo 100% - This was the first shounen romance series I ever read, and so it has a very special place in my heart. The manga is very good (for the first time though; it's not something you can reread), but the anime sucks.
I"s - The second shounen romance series I ever read. Can be overdramatic at times (leaves you kinda going "right. what now?"), but it has a very strong premise and beautiful art. The story execution could be better though.
Salad Days - I'm amazed no one knows about this series. Salad Days isn't so much a series per se, but it basically a collection of high school romance stories. Deals a lot with love, relationships, friendship etc. It's got great art as well.
Suzuka - Another great shounen romance series. Love, ecchi, sports; it's pretty serious, and sometimes the main characters can get a little frustrating, but if this is your type of manga, you will love this one.
To Love Ru - I prefer this one over Mx0. Great cast, awesome humour, and very good artwork. Is about your typical high-school guy (again) who has this giant crush on this cute girl. One day, he goes home and finds a nude girl in his house; the humour centers mainly on her gadgets, and there are LOTS of ecchi moments in this one.
I see we share similar interests in manga, particularly, To Love Ru and Salad Days. By any chance, have you read School of Water Business by the same artist of Salad Days.
GachaGacha, as well as all 3 seasons of Boys Be, deserves some mention too. :)