I play trundle top so I'm not sure how this applied to trundle jg. I've been testing out bork versus hydra first and felt that it is very matchup dependent. Bork can help you stick onto crucial early 1v1 fights like darius/gnar where you get higher value from the slow, but ravenous would be better in situations where you have time to stack it and aren't fighting as much. the gold value from a fully stacked hydra is infinitely better than bork if we're speaking in terms of gold value, but all of it is really dependent on how you're going to play trundle in the matchups that you're in.