I know that PC Engine is better than the Turbo, but PCE is confusing and hard to collect for. I am very intrigued by the history of the American system, and collecting the games with awful box-art would be a lot of fun.
Fun if you like flushing your money down the toilet. Have you seen how many members are looking for the same handful of U.S. games in their signatures? If you're already happily playing the PCE, why would you start collecting TG games
with boxes in 2012? Better to buy a bunch of loose games for PCE, or any system, than a handful of North American TG titles with boxes.
Anyway, you're asking a lot of different questions, so it's hard to answer.
1) the PCE isn't necessary "better", it just has a larger library and lacks the stupid controller incompatibilities.
2) Yes, being able to play both U.S. and JP games is worth it.
3) PCE games are
not more expensive. Other than a few oddballs like Ninja Spirit, Parasol Stars, and Keith Courage, PCE games are much, much more affordable. The list goes on an on: Magical Chase, Dynastic Hero, Cotton, Terraforming, Godzilla, Exile 2, DEII, Super Air Zonk, Soldier Blade, Bomberman 93, Hero Tonma, Shockman, Neutopia 2, etc., etc, can all be had for a fraction of the price of their U.S. counterparts.
So yeah, get a region mod or a TG deck so you can play both regions. If you're an RPG diehard, maybe spring for a handful of the expensive text-heavy titles.
As for the boxes and the set: "abandon all hope..."