Yes, Asia Miles is an excellent Frequent Flyer programme. One particular “sweet spot” is long-haul flights to Europe, which can be had in Business class for as few as 85,000 points on Cathay Pacific, or 90,000 points on other Oneworld airlines. So Asia Miles points are definitely worth accumulating.
Yes, there are plenty of Visa/Mastercard points programmes that can transfer to Asia Miles. The problem is that the transfer rate is pretty ordinary. NAB Rewards, ANZ Rewards, Altitude Rewards, CBA Awards, you name it – they all transfer to Asia Miles at a 3:1 rate. So if you transfer to Asia Miles from these programmes, whatever you gain from the good Asia Miles redemption rate, you’re losing from the lousy transfer rate.
My practice is to only transfer to Asia Miles from AmEx Membership Rewards, which has a 2:1 transfer rate. I generally transfer points earned from my Visa and Mastercard spending to another Frequent Flyer programme such as Velocity or KrisFlyer which I can get 2:1 transfer rates for.
Of course, if you’re after a large number of Asia Miles points as quickly as possible, you could consider signing up for a Visa or Mastercard attached to one of the above programmes with a good sign-up bonus, and you could then transfer the points at the 3:1 rate. But as a general rule, a 3:1 transfer rate isn’t great value.
Hope this helps!