Mohsen Chavoshi , Sami Beigi, and, if you like rap, Erfan, Hichkas, Yas...there is an interesting movie about iranian music scene "No One Knows About Persian Cats" (Kasi az Gorbeha-ye Irani Khabar Nadareh)

If you are looking for top pop singers, I suggest Dariush and Ebi. In young singers I suggest Ehsan Khaje Amiri, Mohsen Yeganeh, Maziyar Fallahi. there are too many pop singers, Dariush and Ebi are the most popular classy singers. My favorite Persian song is: " ShekanjeGar " by Dariush and " Tasvire Roya " again by Dariush. Choosing the best singer of all suggestions depends on you musical taste :)

i'd suggest Mohsen Namju but some singers of old times like Kurosh Yaghmaii and Fereidun Forughi are great

listen to high level artist.expect Googoosh others has not high level.I suggest you listen to EBI , Daryoush. Ofcourse some of them are funny but their poem are cheep.

Salam 25 Band (Gahi Vaght ha),Ebi & Shadmehr(Royaye Ma),Farshid Amin,Kamran & Homan,Farzin ...... I think ,All of them have beautiful songs