I personally really like Hypoc and Pansy
Machine (and Spunj) is the best esport caster hands down and I also really like Medic from LoL, but in Valorant its likely Bren/Sideshow or Pansy/Hypoc. I just don't like most Valorant casters that much because their styles are just bit boring for me (like Pansy/Hypoc). Not that they are bad, but their style is just more passive and calm and I like more hype commentary myself. Pansy/Hypoc has improved lately tho and they aren't as negative as they used to be before so that is big improvement IMO. Bren/Sideshow is just familiar from OW and they have great synergy and explain the game well. They are also more positive than EMEA counterparts usually so it is more enjoyable to listen to.
Tbh Sideshow/Bren, Pansy/Hypoc, Tombizz/Mitch are all pretty equal. Just negatives that: Sideshow/Bren are good, but get bit repetitive and stale at times. Pansy/Hypoc at least used to be really critical and negative and focused a lot on negatives and it made the teams feel bad also not as high energy. And Tombizz/Mitch are all about whimsiness and that can be cool, but again often makes the level of play feel low because they joke about plays and stuff and sometimes it comes out as negative.