Yumas slower but more impactful token creation paired with all the cards it can draw works for a grindy, midrange-style deck while Hazezons more aggressive token production makes it better suited as an aggressive commander
Although this is a combo archeype it is not a win on the spot kind so cards like Pact of Nagation (3.5) are fairly useless
With this in mind, the card from the early previews for War of the Spark that most grabbed my attention is Dreadhorde Invasion: The obvious comparison here is Bitterblossom, but the cards are quite different
That said, the same data carries a warning that most of that money is spread across modest, repeatable sales, not headline-grabbing sales
This is because ramp is in the color green, whose biggest weakness has always been finding ways to get card advantage
+1/+1 counter builds can be pretty effective in this format, especially if you luck into a copy of Terrasymbiosis