I don't know what to choose...

A no-brainer job in data input with security, stability and a chance of promotion or transfer to another area IT related far away in the future...

Or

An intership of one year, in systems analysis, with a 30% better salary but no guarantees after that...

This is just me personally but I'd do the internship and work my butt off and learn as much as possible.

Same, I'd go for the internship, work my arse off, show them I'm worth keeping.
You'll learn a lot about your capabilities and strengths

I don't think us, internet strangers can recommend much. It depends on your current state. Maybe you have been working really hard before and just want to relax right now, thus taking the internship job may lead you to burnout. In my opinion, it completely depends on how you feel about the jobs.

I'll do the internship but, eh, that's your choice mate.