I love Gen V's cries myself. They're all very fitting, from Musharna's psychadelic mumblings, to Gothitelle's Psycho chords to Scrafty's "Come at me, bro!" there's plenty of variety to go around. Special props goes to Krokorok's awesome electric guitar riff cries.
Anyone who says Gen I is strange, though. Some of them are really ear-piercing (here's lookin' atchu, Raichu) and some are just lazily reused (Charizard and Rhyhorn and Parasect and Mewtwo are the most obvious). I'm in the camp who thinks that the games have just gotten better with every new generation, so take that as you will.