Don't worry about resale value now, because as has been mentioned, an XR will hold its value better than a Ghia, however you have to pay more to start off with

So either buy cheaper & sell for less for a Ghia, or pay more & get more back (hopefully) for an XR
I'd go the Ghia anyday. And if you want to see a really tough Ghia (albeit a V8), check out "Stevo"'s black EL Ghia on the other forums (.au). It's an EL Ghia with an XR front and a GT spoiler (I think), and I think the sideskirts and rear bar may be XR or GT as well... Looks fkn tough!
EL Ghia motor vs XR: 161kw/164kw <-- get an exhaust for either and they will probably end up being the same, as the Ghias have a more restrictive exhaust so start off with
EL Ghia diff vs XR: both 3.45LSD I'm lead to believe
XR has bodykit & front, but Ghia has all the interior fruit. Which is easier to swap over? A kit is waaaaay easier than trying to install a high series dash, leather interior, electric everything, etc etc
5 spd vs auto? Do a T5 conversion, or put a 3.7 or shorter diff under the EL (plus a shift kit) and it'll beat a manual no worries, while still having a good cruising RPM (due to auto's 0.68 4th gear vs T5's 0.78 5th gear...)
Best of luck with your decision! Nothing is wrong with an EL XR, but unless you're buying from new, a Ghia will be better overall value than an XR, especially when the cars are 8 years old now!
-Dave-