I have no problems with Japanese, so I guess I'll jump into Z1. If I don't like it at least it'll cost me less money.
Haha, absolutely :-D Z1 is definitely a very good one, and since it's the start, might as well take the time to go through it. Though now in retrospect it really feels they intentionally left plot threads hanging back then, but had no real plans on how to actually use them, and it's from Z2 onwards that they tried to design everything coherently - but ultimately, it makes Z1 feel pretty different from Z2+ (doesn't help that most of the cast list from Z2 sticks around from then on, while Z1's had some confusing disappearing acts).
Still, definitely good enough to warrant at least one, and maybe multiple playthroughs, before moving on to the rest!