Best option to make MMORPG Server with blitztech?

BlitzMax. You get raw access to the sockets. You can write your own socket code in C++ if you need ultra-high performance socket code such as that provided with IOCP, and call it via BlitzMax. And, BlitzMax is object oriented, something that will become a practical necessity in an MMO of any size.

I'm sure there are other reasons as I'm not all that familiar with BlitzPlus. But i guarantee Max is the better choice here.