Realistically I think he hates Vickers the most. I'm pretty sure Gator said the same when he was on Kino Casino.
Vickers has brought more of Ralph's dirty laundry to light than most other people on the list, excluding Ade.
And while everyone else has collectively damaged Ralph's reputation, viewership, and paypig numbers, Vickers is the only one directly going after his wallet with frivolous and not-so-frivolous lawsuits, as well as child support. That's not even getting into him using Xander to fuck with Ralph, something even alot of Kiwis and A-logs think is going to far.
Also, I can say with a fair amount of certainty Josh is higher on the list than PPP.
In Gator's leaked texts, Ralph actually sounded quite regretful that he couldn't work with PPP, and that he wished they could team up against Josh.
Ralph probably sees a kindred spirit in PPP, they're both big into the wrestling showmanship and kayfabe shit, they're both fat weirdos obsessed with drama. Hell he might even write off some of PPP's criticisms as some form of kayfabe.
And they've been known to work together and even ease off at times (PPP talks about easing off of Ralph and teaming up with him to go after Tea clips because he wanted to do a RV with Ralph (this was before the Faith arc), Flamencogeddon, the Warski fight, etc.)
Ralph and Josh are very different, so there's an inherent clash.
Josh doesn't like kayfabe or showmanship, what he says is usually what he thinks, so you can't write off his criticisms as him playing things up.
And on top of that, unlike PPP who has been a-logging Ralph for nonstop for years, Josh used to be on good terms with him, and when they were friends, the Kiwifarms wasn't going at him very hard.
This not only adds an element of betrayal, but Ralph probably sees Josh as controlling the sentiments of Kiwifarms, so he thinks that when Josh turned against him, Kiwifarms followed suit.
Metokur and Gator are weird cases. My gut instinct tells me Ralph can't bring himself to really hate either of them, since they contributed so much to the success of his show, and he clearly viewed both of them as close friends.
I also try thinking logically, that compared to PPP who's been a-hogging Ralph for around 4 years, Josh who's been doing so for 2, he wouldn't have as much resentment built up towards Metokur and Gator who have only been a-hogging him for a couple months.
But this is Ralph we're talking about, so logical thinking is already out the window. Ralph might think of it in terms of how significant their betrayal is, in which case Metokur and Gator are easily the most significant betrayals he'll ever have.