10
Best of the series. It's a great stalker horror movie in it's own right and feels a lot more real than T2. Even with the time travel, Terminator feels like it could actually happen and there's a gripping sense of dread throughout.
I'd give T2 a 10 as well but damn that movie is long, the special editions in particular seem like a marathon at times. It's certainly great but it's a little more fantastical than the original and my suspension of disbelief doesn't go quite as far. Terminator hits the sweet spot for runtime and has better mystery surrounding future events.