I don’t know if it helps you but I’ve obtained a negative conversion rate on SGD to TWD.
This means that I basically got 3.5% over the mid market rates. It is the first time in my life when I earn more by exchanging money instead of paying so I was kind of expected. At $100.000 TWD, that’s $3.500 TWD so not bad.
As far as MYR, best currency to exchange is always SGD in Johor Bahru. The rates are phenomenal and far better than what you would get in KL.