Currently Which is the best 16 (or dual 8) core processor in market right now? we are planning to use it for multi-threading operation.
"Best" is a relative term. You can use the processor feature filter to help select a processor.
I have done some minimal filtering here:
https://ark.intel.com/Search/FeatureFilter?productType=processors&CoreCountMin=8&CoreCountMax=16 Intel® Product Specification Advanced Search