Theres numerous reasons why Paradox Rift is the best choice right now for competitive players and collectors but the main one is that its the most recent set, with the newest mechanics and keywords
Since the card is currently only being played in just one modern deck, I personally had it in the third spot behind the best blue reactive spells in the format, Counterspell and Force of Negation, but I can see the number one spot going to the best and most efficient threat the color has to offer
Mechanically, I want to play this card
Mewoscarada, Giratina Ex, Red, Pokemon Center Lady, and Iono are all worth collecting, but with Darktina decks mostly out of the meta, Giratina Ex is seeing a lot less play, and the supporters are typically played in single copies
Whether youre a filthy casual, a competitive cEDH player, or somewhere in between these two stereotypes like me, efficiency is always a part of the conversation surrounding deck construction or deciding which preconstructed deck to buy