What is the world's second best business class?

It gets pretty subjective especially given the preponderance of Rockwell Super Diamond and Thomson Vantage XL seats across a number of airlines meaning the hard products are very similar. It would probably be easier to develop a Top 10 and, were you to do so, I think both VA and QF would make appearances.

1st would most definitely be QSuites as you mentioned, but the 2nd is actually British Airways first class. It might not actually be business class, but the hard product certainly makes you think so, the soft product is excellant with freindly service and caviar. From there, I guess any plane with a 1-2-1 config and decent soft product would be good like QF, DL, United Polaris, CX, etc.

I would say the Etihad Business studio.

Etihad A380. In all classes probably the beat aircraft in the sky.

Interesting question. Qatar's A380 business class is really great, I'd agree that Etihad's A380 business class is the only one which could give it a run for its money so maybe there are your 2nd and 3rd medal winners right there. Now 4th place and beyond would be tricky. I would put Qantas' Boeing 787 Business Suite in there, followed by Cathay Pacific's A350. Haven't flown any of the Japanese airlines but here good things about ANA's latest business class too.

Its hard to look past the new Singapore airlines a380 product

JQ star class for sure, or the old red seats from Virgin...

VA A330 or 777 great food, fantastic amenities, unparalleled service and amazing 1-2-1 reverse herringbone private and comfortable with lots of storage seats

Would have to disagree with Etihad Business as their cost cutting has really taken a toll. The hard product is still good, however found the seat to be a little firm (even after adjusting the firmness) and lack of kneeroom was prevalent. I would argue that VA is quite good because of their hard and soft product, but it is available on very few routes. JAL should be next, along with Eva Air, United Polaris, Delta, ANA, Singapore and Cathay in that order.

JAL Apex suites. Direct aisle access for all. Forward facing. Very private. No silly rabbit hutches or crevices to fit your feet into.

I suspect the OP meant international business, which makes REX ineligible...I'd say EK a380 business if we're sticking to seats that are actually sold as business. But QF first is really just business these days when compared to QSuite. So QF first is my vote for 2nd place, made in the same vein as djtech has done for BA first.

Oman Air/JAL. It's the same seat.

I would have to say that I am very impressed with the new Qantas Business Class seat on their Airbus A330 and Boeing Dreamliner. I have just taken two flights with this product and am impressed - much better than the product on the A380 or Jumbo in my opinion (despite the wonderful legroom the shell design provides). I also like the Qantas service - personally, I am not one for over-attentive cabin crew that ask every 30 minutes if I am OK - if I need something I will get up out of my seat and ask or will use the call button. Mind you, I see a plane as a method of transport to get from A to B - it is not meant to be a hotel room, so I do not necessarily look for cabin suites, on-board showers etc (but fair call to those who seek such amenities) so my comments reflect that view.