Xilinx ISE. Admittedly I only used it for a college course ~1.5 years ago, and then only whatever version they made freely downloadable, but it was ridiculously

Xilinx ISE. Admittedly I only used it for a college course ~1.5 years ago, and then only whatever version they made freely downloadable, but it was ridiculously buggy and user-unfriendly compared to any other development tool I've tried.