Translation:Playing volleyball is my favorite exercise.
"Playing volleyball is my most favorite exercise" would be accepted, or must 最 be ignored? Posted on Nov. 19, 2017.
As far as I know favorite when used as an adjective, comparative forms are not used because the word already has the 'most' meaning in it. It is probably not acceptable to say More favorite or Most favorite. So Duo's is a justifiable translation.
We can suggest an alternative like Playing volleyball is the sport I like the most.
2 things bother me:
Volleyball is a sport but is Playing volleyball a sport?
In Japanese they don't accept Sport for 体操, only Exercise; How come they translate 運動 to exercise now?
Keith_APP is correct. While some people do say 'most favourite' this is not correct English, as 'favourite' on its own already describes the thing you like the most.
I don't recall ever hearing volleyball referred to as an "exercise". Only a "sport". Probably it is because I never think of something as being an "exercise" unless you can do it by yourself, which isn't possible in the case of volleyball.