I wouldn’t really prioritise any of the roller coasters at the park. All 4 major coasters are top tier rides in their respective category. I’m one of the weird few that enjoy Raven over Voyage. I know a bunch of huge Legend fans too. There aren’t too many flat rides that jump out but if you’re a super cool person you’ll probably want to hop on the hilariously themed Turkey Whirl just for the shits and giggles. Gobbler Getaway is a ton of fun too.
If you’re trying to do the waterpark on the same Saturday you’re going to the dry park, then probably not. To be frank, Splashin Safari is one of the few waterparks that I would consider a full day waterpark. So many awesome rides in Splashin Safari that you probably haven’t seen at other parks. You can probably get to Holiday World after 3pm and be just fine getting the rest of the dry park done. I’d probably get to the park at open if you were planning to do everything in the water park.