How do I into pokémon?

I've been lurking for quite a while and want to get involved again.

>Pokémon GO!!!!!111!!!One!!
Pls no

I've played Pokémon red and fire red so Gen 1 was enjoyable but when I tried Gen 2 a couple of years ago I hated it. My questions are:

>Should I just jump into Gen 3 and work my way up?
Or
>Should I go for the latest Gen and work down
>Are ROMs any good and should I play them.

Also for now I'm into the normal games that came out as part of the series, so I don't feel like the obscure spin-offs would be particularly helpful.

Thanks anons x