Ding ding ding!

This is what I thought of immediately. A layout that is in many ways "similar" to TAF which you noted as a good thing, a really popular machine for new players, difficult enough but not impossible, can easily have longer ball times...

As for your choices, NGG still has some code issues that eliminate it from consideration for me. Congo I just never quite understood the draw of. Tommy I own, but think that JP is by far the superior game to it as it stands right now.

However, no answer is going to be wrong

I missed this before, sorry, but in short I like JP more than Tommy because...

1) The Tommy video mode, which has no skill in it what so ever, drives me batty. I HATE that.
2) A decent number of the Tommy modes are very similar to one another in the way of feel. They are also very similar to modes on JP - I love DE machines, but DE recycled their code *a lot*. I own JP, Tommy, TFTC and WWFRR, and all four have almost identical modes, you just have to shoot to different spots.
3) JP's toy is amazing. While I like the blinders idea on Tommy, I think the dino is cooler.
4) Multiball progression on JP seems a lot more obtainable than the upper ramp on Tommy, that seems so stupid hard to hit.

I had them both side by side for a while, and Tommy easily left first. I still own it, but it's not in the current "mini arcade."

As for your other question... roadshow, tommy, congo, Jurassic Park, Baywatch, Last Action Hero for me are like this:

JP, Baywatch, Tommy, Congo, Last Action Hero, Roadshow.

I own the first three, and the gameplay on Baywatch is outstanding, but it's ugly as heck. Tommy I just detailed. Congo is okay, but I don't like the geometry of it that much. LAH has very similar rules to JP and Tommy (and TFTC and WWFRR) which I already own, so no need to be interested in that. And finally, Roadshow I have never found a machine that I cannot play for WAY TOO LONG. No interest in that one.