The variation in hard product in business class, makes it necessary to do research on what you are actually buying.
For instance, the business class product on Kuwait Airways is inferior to the Premium Economy product on Qantas....
The best business class I've flown with, and I may be biased, is Oman Air. Although they were awarded by several organisations for being the best business class in the world.
I generally look for fully flat, and my preference to is generally Etihad since all the aircraft offer the same lieflat cubicals which ALL have aisle access, and they also offer as you wish dining.
For service, I found Asiana the best.
With non fully flat seats I barely see the point in flying business since I know I won't sleep.
Also not overly keen on the herringbone arrangement by some airline such as Cathay.