hey
Xilinx ISE is good.Its quite a heavy software as compared to many others but then thats a small price paid for advantages like graphical input testbench and performance.
I guess it really depends on how deep is your pocket. However for me Xlinix ISE Webpack is something that is great however it has its fair shair of bugs. Currently I am using it with Spartan 3, and it is releatively easy to use that quite straightforward with excellent support from Xlinix however if you are richer I guess proably can consider Modelsim for the simulation part.