That exact reason is why I think IV is worse than all the PS2 titles. I don't want to be able to distinguish between the cracking of a tibia and fibia as I hit someone with a car, I want them to bounce off it in a cloud of unfocused comedy gore. Before IV GTA was bright, colourful and daft, and that's what I want from a sandbox crime game - things breaking easily when I drive into them (apart, of course, from the car I'm driving), over the top explosions, the ability to swim underwater for ridiculous periods of time and take multiple bullets to the head and not die. I personally find looking for weapons and such floating in glowing spheres is a lot more fun than trying to work out whether what looks like a brown gun leaning against a brown wall in brown light is a gun, or a stick, or a shadow. Something SA onwards was guilty of, and unfortunately has been continued into IV, is dating and suchlike; I just want to blow things up and kill humanoid shapes, not spend time doing things I could (and should!) be doing in real life.
And, of course, I don't want my cousin calling me up every 10 damn minutes.
Asides, then: my favourite GTA, then, would be Vice City in the size and replay value of San Andreas. Also, the first GTA had an expansion pack set in London, the only GTA I'm aware of set outside America.