I personally feel that a round handle naturally fits well in the human hand. The grip and hold is a lot more easy and comfortable. The bat is a lot easy and simple to maneuver with a round handle as per the anatomy of a human hand.
Many other players may find oval or semi oval handle better. Which is all good.
My question is, if I remember correctly, it used to be round handles only.
And the oval or semi oval came in as a marketing ploy in the name of innovation. Folks then slowly started to pick the idea.
The idea is, it helps stop the twist.
My argument is, if it helps stop the twist then it may also create some hindrance when you actually DO WANT to slightly twist the bat and get the right angle to play the intended stroke.
But also and more curiously, if the bat has a rubber grip and you are wearing gloves where the leathers in the palms provides some excellent traction, why would the bat twist so much in your hands that you need an oval handle?