Personally, I'd say the one that would be worth more to you when you want to sell it, will be the one that costs you less to put in (if that makes sense).
Basically what I mean is:
- Take said car with 18RGEU (which I assume you already have)
- Compare cost of getting a good turbo setup running reliably in it, vs. the cost of a 1G conversion (how much of all this you can do yourself I don't know)
- Market value of the each resultant car will be pretty much the same really. 1G may attract more $$$ based on the fact that it's a factory engine, however if the 18RGTEU is proven to be set up properly, it may pull in the right money from the right buyer.
- IF however you have to spend $2000-$3000 more on getting the 1G in than you will on turbo'ing the current engine, then it's not going to be worth it come sale time.
At the end of the day though, if you're worried about resale value of your car, you shouldn't be modifying it in the first place.