Big Mess o’ Wires compared Xilinx and Altera’s FPGA tools:
I used to believe that Altera’s FPGA tools were much more hobbyist-friendly than the comparable Xilinx tools, and I frequently bashed the Xilinx tools whenever the topic came up. But after giving them a head-to-head comparison recently, I think I may have to eat my words. The truth is they’re both pretty rough and clunky, and difficult for a beginner to get the hang of, but the Xilinx tools are definitely superior in some important areas.