Some cards are particularly valuable for collectors, while others are preferred for their game mechanics
GX introduced stronger effects, ultra-rare cards, and once-per-game GX attacks, while Pokmon EX cards were strong basics with simpler mechanics
SR Super Rare UR Ultra Rare SE Secret Rare UL Ultimate Rare PS Platinum Secret Rare CR COLLECTOR'S RARE QCSE Quarter Century Secret Rare Nadir Servant X SPELL Send 1 monster from your Extra Deck to the GY, then add 1 "Dogmatika" monster or "Fallen of Albaz" from your Deck or GY to your hand, that has ATK less than or equal to that sent monster in the GY, also, for the rest of this turn after this card resolves, you cannot Special Summon from the Extra Deck
All of these factors make it a valuable card to include in your deck
Each and every game will require the player to predict their opponent's plays while also strategically placing their own limited number of cards
Others, like Ravager's Mace or Kabira Outrider, buff your creatures equal to the number of creatures you have in your Party