I also played every gen. If you really want to play them all, then I recommend to start with:
1) Fire Red/Leaf Green
2) HeartGold/SoulSilver
3) Emerald
4) Platinum
5) White/Black
PS. But I don't think this is a good idea to play a lot of pretty similar Pokemon games back to back.
Start with Platinum or White/Black. U dont need to play them all or even every gen.