I am very interested in them from a gameplay perspective, however narratively I'm a bit less enthusiastic. Which kind of sucks, since the reason I find the gameplay interesting is because of how it relates to the storytelling, but this story in particular doesn't look very cool.
1 is really tedious and boring in a modern context. I beat it for the first time a few years ago, and felt like it was kind of a waste of time. If you have no nostalgia for it then you will probably only enjoy it as a historical curiosity.
2 is the game I have the least experience with. I've played the first couple hours maybe 3 times and something different made me give up on it each time.
3 is just like 5, but not as good.
4 is alright. I played it again earlier this year and I don't think it holds up as well as people seem to think it does. A lot of my enjoyment came from my nostalgia for the game. Lots of people like to recommend the DS version because it has better graphics, but bear in mind that they made the DS version much harder and grindier than the original.
I chose Y because I have a Y in my name, and because I like the color red better than blue. The legendary looks a bit cooler as well, though I expect he will be less useful. Mewtwo Y is also the superior looking version, though it's kinda lame he doesn't get a secondary type too.