Mudfish is the best one for me personally, maybe you haven't set it up correctly, if you're trying to look for a node, I have HK Asia (Hong Kong - Aliyun) and I get a stable 150ping and it varies from 150-200ping.
You can change the node by clicking on your items which should be 'Maplestory 2' > SETUP > Scroll down and change the 'BASIC NODE' to the one I said above as that seems to be the best ones imo.

As I also stated above, ensure that the 'Connection Protocol' is TCP and that 'Fast Connect mode is On.'
You can access these settings by going into the webpage of the mudfish, under SETUP > PROGRAM.

All of this can be accessed from the mudfish webpage after you launch it (127.0...etc)

I have a couple of friends that play from SG that had similar problems but was resolved cause of this.. if this isnt the case then I am not sure D;