I traded for the 3G OLED model not long after its launch. I also picked up a blue Slim a couple of years ago as a back up.
But last year I softmodded my 3G OLED, removed the 3G device and installed an SD card. It's so great! This is the only model where there can be an SD card and still use the Vita card slot for games. The added space is godsend just for updates and game saves. I have gone a bit of a spending spree too, now that everything is on one SD card. Before that I can a 32GB card for Vita games, a 32 GB card for PSP games and a 16GB card for PSone games. Such a hassle.