What is a commander you dislike, despite seeing it mentioned quite often?

For me, it is Omnath, all versions.
While I do like the art, I really dislike how Omnath players never use any device to inform opponents how much 'unspent' mana they have to their disposal. It feels like a cheap method to gain an unfair advantage. It becomes unbearable to keep track of. I can't help but roll my eyes, assume they have unlimited mana, and just hope they get taken down quickly.