This one is probably perfect for @
corporate-wage-slave to answer.
My feeling is that none of the lounges at LHR are special enough to factor in a decision how you fly to/from LHR. I'd pick convenience first. So if your flights are T5 based, it's a lot nicer NOT to have to shuffle over to T3. Especially if you fly back from a UK airport to T5, you avoid having to clear security again unless you transfer over to T3 (even if it's an airside transfer, security clearance is still needed).
Now with that out of the way, I do like the CX First class lounge at LHR T3, but it is a little busier than CCR in T5.
If you do go to CCR, you might be lucky enough to meet @
corporate-wage-slave there, it's his second home.
