Outside of the first few months (where I didn't have a VGA cable) I ONLY used the VGA cable on a monitor. In fact, I actually found that I preferred using an SDTV with s-video but didn't have a choice. You see, the VGA adapter WAS sharp, but it also revealed all of the visuals flaws in games that were otherwise hidden when viewed on an SDTV. So, I had mixed feelings about the VGA adapter. That said, Rez did look really sweet on a VGA monitor due to its visual style (things like dithering were not obvious with the game). However, the quality of the colors wasn't all that different from the PS2 when using component on that system. The image quality was obviously better, but again, I'm a framerate whore and I never found the interlaced appearance of PS2 games to be all that unattractive at the time anyways.
You wouldn't know it, but back then, I was actually a hardcore Sega fan. I really hated the PS2 for a while after its release. It wasn't until I saw some of the more advanced PS2 software that I started to accept it and become impressed by it. I remember holding up shots of Shenmue against the MGS2 trailer in 2000, but I couldn't deny it, when I played the MGS2 demo at 60 fps with those visuals, I knew the DC just couldn't stand up. I don't think I've ever been as impressed with a game as that. It literally felt like something from the future (and it still holds up beautifully to this day).
DC was the machine that brought 60 fps into the home and PS2 took it even further. It's a shame that things started to change over time, though, and this generation is so devoid of high framerate titles.