I was just kidding since no amount of evidence would change his mind. And I disagree, GTA4 was worse than the trilogy on PS2.
GTA IV was objectively technically better in every way in terms of gameplay, visuals and controls. It's a good game that still holds up far better today than the PS2 trilogy.
It also had the best story of the series, but that's obviously subjective.
Personally, I feel like GTA III barely had any story worth even mentioning, Vice City completely ripped off Scarface, and San Andreas was a sloppy mish mash of 90's rap, it's culture and movies that started out strong and petered out well before the end. None of these games stories(the environmental and Lazlo-esque stuff is always hilarious) are well written save for some choice lines in San Andreas, IMO. Fun to fuck around in, but they don't hold up quite the same way that IV does. Hell, even the DLC has better writing, missions and stories. The Ballad of Gay Tony and The Lost and The Damned are both top shelf GTA. This was Rockstars peak, IMHO.
GTA V was a major letdown in this department for me the way the story and branching narrative bullshit was implemented, and a lot of the physics systems and other actual gameplay stuff was a step back from IV as well.
Not trying to have a GTA argument here, but saying that "GTA4 was worse than the trilogy on PS2" cannot go unchecked.