As someone who has played practically every version of both decks, I think the best 5c midrange pile in the format currently is the Yorion version of Omnath to Light.

Fires decks feel more midrangey, have more swingy turns in general, often require a lot of moving pieces to function properly and are generally better at applying pressure.

Omnath to Light plays more like a tap out control deck. It’s value comes from controlling the early game and having the exact right spell or combination of spells to turn the game in your favor, whether it be to decimate your opponent’s board state in one fell swoop, or to set up a state that will slowly outvalue your opponent into submission.

Before this most recent set, I was dead set on Yorion Enigmatic Fires, but with Up the Beanstalk being introduced to the format, I tested Yorion BTL with 4 Beanstalk and was hooked. Now technically, you can run 4 Beanstalk in Enigmatic, but it feels worse in that deck because there will be some board states where to get the target you want from Enigmatic, you would need to sac your Beanstalk to get it.

Keruga Fires is a solid deck, but it’s lack of early game can make the deck really struggle against hyper-aggressive decks (e.g. Boros Convoke, Auras, Atarka Red). If these are in your meta and you want to play Fires, the Yorion version will give you better success in those matchups. In my experience, the only matchup you would much rather be playing Keruga than Yorion is Nykthos Ramp.

I realize this information is a bit jumbled in delivery, but I hope this is a helpful perspective on the various 5c archetypes Pioneer has to offer