Abilities like double strike, unblockable, and toxic are all relevant, and power buffs can also help you aim for that commander damage win condition
REWARD YOURSELF FOR THE COMMITMENT Ive covered a couple of good reasons to run chunky Commanders already, like Traverse the Outlands, but you should take every card that rewards you for committing
Mickey Mouse, Brave Little Tailor packs five strength and five willpower
(They can't be blocked as long as defending player controls an Island.) Creature - Horror Squid Detective of the Month Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.) As long as you have the city's blessing, Detectives you control can't be blocked
A single treasure from a card like Prosperous Innkeeper can push you ahead one turn, enough to turn the tide of a game in your favor
In one way or another, these all qualify as among the very best cards in Rise of the Floodborn