I would suggest not to use any ready-to-use-conversion-tools but rather learn the differences and convert the hosts manually one by one. It took me a couple of days to convert all of our sites to nginx and two weeks more to realize the differences of Apache and Nginx handling very specific cases, such as PHP environment in particular scenario where old PHP scripts would rely on SCRIPT_URI/SCRIPT_URL that is not available in nginx, or scripts using PATH_INFO/PATH_TRANSLATED, and these have to be correctly set.

If you do not want to spend valuable time for learning and adopting, you may always rely on reliable users with experience ;)

Andrejs
loco (at) andrews.lv