OK! I prefer RISC architecture myself. But you should notice that the architecture you use, depend on application you have.
Read the attached .pdf document to see performance of todays softcore processors.
Note that LEON is a very good and powerful softprocessor that is freely available! this is my popular one visit "http://www.gaisler.com/" for more information.
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Again uploaded stuff from web and wasted serverspace!!!
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As for the type of cores, more risc type are done in FPGA such as ARM or PowerPC, haven't seen cisc or x86 on FPGAs as much. Leon is a popular VHDL core specially for space engineering applications.