These are the first bands that came to my mind when I thought about artists that definitely need more recognition. I would have added more, but I didn't want this to turn into a wall of text :D
Mgla is a black metal band with some extremely nice melodies that, however, do not hinder the sometimes claustrophobic experience they are able to provide you.
Bulldozer is one of the "italian thrash metal triad" bands (the other ones being Necrodeath and Schizo) and they are one of the thrash metal I enjoy the most. Sometimes motoread-ish, sometimes with a punk attitude, alway fast.
Ceremonial Oath is a melodic death metal band that featured some young guys that would end up later on creating In Flames and Hammerfall. This is a band that I hardly see mentioned, but if you like early In Flames stuff like I do (especially Lunar Strain and Subterranean) you will find some extremely nice tunes.
Sigh is just a crazy band. Mainly a black metal, they experimented A LOT during their career. Fast songs, songs with classical music feel, songs with saxophones? You name it. This is one of their most "normal" tunes but one of their best ones imho.
Artillery is such a good band. Some albums hit like a punch in the face, while other ones have a strong emphasis on melody and arabic scales.