I'm bias but I'd get the diesel everytime.
The only reasons why I wished I'd of gone for the EX is for the 17" alloys (although a firmer ride) and the
HID lights (are they really that important though?!).
I love my ES, with its funky roof and the minor mods I've done to it. The only other things (IIRC) of note missing from the EX spec is Sat Nav (already bought Tom Tom relatively cheeply) and the hands free (can get that installed at Halfords for £100).
Bear in mind the sell on value as well - I think the 2.2 will arguably have a higher sell on value (prob not much though) due to the bigger engine (I may be completely wrong there so feel free to correct me).