The first release came out with just 36 cards (part 2 onwards had 151 for this generation (excluding the 2018 reprint)), so it wasnt a very weighty release and only developed into a massive, branded product line, over time (which it now is: with more than 300 million units sold over its lifespan (Japan has 126 million citizens))
UB can play off the same strong commons and uncommons as UR does, and it has some great expensive spells to pair them with like Sephiroth's Intervention, Ice Magic, Dreams of Laguna (flashback), and Sidequest: Hunt the Mark
This one has a lot of appeal to collectors, however, thanks to its prehistoric vibes, and its undoubtedly going to be worth a lot of money when Temporal Forces first launches
A Few Good Options There are a couple of cards that just seem good here being thematic and also highly synergistic
In Final Fantasy VII Remake , the party can spend a bit more time here, but Seventh Heaven itself continues to make up only a small amount of the game overall
Every person who buys a Miku lair after it sells out is a buyer that Wizards could have made money from