It depends what you mean by 'Best'. The only direct service from the UK is Malaysia Airlines, who are very good, I've flown with them a number of times. They are not the cheapest though. You'll get a cheaper connecting flight from any number of carriers - Emirates, Singapore, Gulf Air and so on.

I live and work in Johor Bahru and when travelling back and forth between Edinburgh and here I fly with KLM through Singapore. Price is the main factor and I find them consistently cheapest. You don't say where your departure point is but I assume it is the UK.

Your question was for the best airline and I would not give that title to KLM however they give good value for money and transfer through Amsterdam is very easy in comparison to Heathrow or Paris.