Honestly, I'm not sure the current mainstream Argentine scene is any good at all.
I would suggest looking up Los Piojos, Patricio Rey & Sus Redonditos de Ricota, La Vela Puerca--
In the seventies and eighties, Charly Garcia and Luis Alberto Spinetta (who collaborated in one band and then had others before they both went solo) were the shit. Charly can sometimes be a little more pop, but all his music is awesome (un his album "Say No More" which I found boring as fuuuuuuuuuuuuuuuu).
Look up Spinetta Jade or Pescado Rabioso. Also Almendra. Those are all Spinetta bands.
Parte de la Religion es probably my favorite Charly Garcia album, but Piano Bar and Clics Modernos are both really up there, too.
Let me know what you think.