Black. I havent restarted and wont anytime soon. It holds all my important pokemon from Platinum, Heartgold, and White. It also has every us c-gear to this day.
I started after finding a Ruby cart on the floor, and I reckon it was a godsend. 8 years on, and I'm still loving the game. Just restarted another run on it, actually, and I still own AL the Sceptile. I even remember why I called it AL. It was named after the Finding Nemo dentist
To be honest, I had my first experience playing on my brother's Gold version, but I officially played my own starting with Leafgreen. Then, I played Pearl and went backwards, trying out Sapphire and Emerald. Then continued on from there..