Rowley has worked wonders for sure. Losing Croft and Ackers would have been a hammer blow to many teams, but Salford are somehow just as competitive without them. I would say though that for Salford's sake he should stay there. I'd be terrified at the thought of him leaving if I were a Salford fan.
Having said that, bringing in an experienced NRL coach like Arthur would be very different to Rohan. He will have the respect of all the Aussies/Kiwis from his time at Parra, similar to Sam Burgess at Wire. He'll also no doubt have a clearer view of who might be available and do well in SL from around the NRL, and has experience of coaching a big club. The downside is that he didn't win a Premiership, but even on paper he never had the best squad in the competition.
I can't see past those two. Demetriou blew a lot of his credit at Souths, letting cliques build up and treating some players
differently to others, which is why Burgess left.
Personally I'd go for Arthur. But would be happy with Rowley.