Yes, if we are talking about domestic competitions then you'll talk about SA's Curry Cup, NZ's ITM Cup and Aussies' newly established competition. I get why you added Super rugby though as it was essentially doubling as Aussies domestic league till now.. maybe still even.
I havn't watched a lot of the Japanese Top league or Rabodirect so I couldn't talk about them. ITM Cup and AP I also only watch the finals so I could only comment on the Top 14 and Curry Cup and its difficult to make comparisons though since the resources involved aren't comparable at all and though you get some good rugby in the CC amongst the top teams its not comparable to the intensity and quality of opposition of the top teams of the Top 14. The Curry Cup has suffered a lot the last few years from a mass exodus of our middle order talent to Europe and its timing to accommodate the extended Super rugby and internationals meaning our test players also don't play in the league any more. So, I guess as an attempt to answer your question from my own framework of reference it'd be the Top 14.
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I'll put a poll up as this seems like the perfect thread for it and it might add to discussions..