Recommended Fortiweb firmware version

Hi,

I need to install a FortiWeb from the beginning... Could you tell me which firmware version would you install from the list?

I need something stable... :)

FortiWeb 5.5 5.5.0 Build 0697

FortiWeb 5.4 5.4.1 Build 0560 5.4.0 Build 0541

FortiWeb 5.3

5.3.8 Build 0491

5.3.7 Build 0478

Thanks!!