you can see comparison and make your choice
Overall conclusion
Participant Speed (r/sec) Memory usage (MB)
Apache (prefork MPM) + Phusion Passenger 444.88 240.0
Apache (worker MPM) + Phusion Passenger 452.10 238.5
Nginx + Mongrel Cluster 354.80 227.0
Nginx + Thin 458.0 228.0
LiteSpeed 470.03 334.0
Apache (worker MPM) + Ruby Enterprise
Edition + Phusion Passenger 564.30 163.5