Berserk The Best Seinen Adventure Manga. (Heavy violence/gore.... Romance is somewhat there).
Shonen:
Magician (KIM Sarae) Fits your requirements completly. Dont let the starting artwork turns you off. (Read it on Batoto as this is a webcomic and they are best when viewed in one strip format).
Tower of God Another one of the best series (A webcomic----> Read it in one strip format for best viewing experiences).
ID Fits your requirenents completly though there is a little romance (& personally speaking I find it too much dragged on).
The main ones that spring to mind are Magi and Saiyuki. Tsubasa reservoir chronicles is a good example but it has romance. Though I thought I'd recommend it anyways because I love it and its a good example of a small travelling group. Heres the list i can think of, though sometimes the groups get a lot bigger later:
Kisswood +Anima Ubel blatt Takeru sword of susanoh Hatenkou Yuugi Beyond the beyond Superior Telepathic wanderers
