I don't know why but this has to be one of the most common questions raised here, in admittedly various different shades - as is the case here.

For a lunch time (ish) session then CX is a good option, particularly if you like noodles / Asian cuisine, and you're looking for a bit of a change. T3 Galleries food option very closely matches T5.

I can't see the point in going to AA / Admirals - it will be quite crowded at that time - other than by popular repute they have the fastest broadband going.