I think that Niv-Mizzet, Parun is the best of the three because it manages to be a huge threat while also being a soft way to control what your opponents do
This card is likely a reference to Goblin Rock Sled, a weird card from The Dark that also features a goblin having fun but in a much less snowy way
If youre hoping to pad out your collection with valuable full-arts and illustrations, make sure to take a look at the priciest picks from Prismatic Evolutions and The Glory of Team Rocket
Dartz, however, is more powerful than the three Swordsmen combined - not only is he able to repel the "Master of Dragon Soldier", a fusion of two of Kaiba's and the Pharaoh's most powerful cards, but is able to expand the full power of "The Seal of Orichalcos", by playing its 2nd and 3rd levels: "Orichalcos Deuteros" and "Orichalcos Tritos"
Once the practice sessions indicate that a students achieved fluency, the program will repeat the entire cycle with subtraction, followed by multiplication and division