Ultimately, thanks to being an iconic character who can actually see play, its no surprise that The Master, Transcendent is popular
If its not in writing (or photographed), it never happened
Hidden Cove and Rapunzel also add to the Will Power of your characters, which will come in handy so you can keep them around long enough to make an impact
To store individual cards with extra protection, you'll want to get some top loaders (a few manufacturers also make side loaders)
Which cards are you looking forward to drafting or cracking in your Prerelease kits
Sticking a 6/6 flyer and then casting Armageddon might be enough in 60-card Constructed, but in Commander thatll mean several turns of uninterrupted swinging, but probably no actual player removal before the pod catches up, or destroys Numot