Love your enthusiasm! You’re definitely in the right place to just have a great time discussing pokemon, welcome!
As for favorite thing that’s definitely tough for me to pin down. I fancy myself a Pokémon Historian and I try to reflect that in my collection. Collecting all kinds of things from pokemon’s history no matter how small as I just love the franchise and find its history to be so rich. That being said I would have to say
As said the story is just so special to me. Its my own personal history of me and my dad just enjoying life and pulling my favorite Pokémon. Wont be something I’ll forget.