For Gothic 2, obviously.
Am I the only one who thinks so? I've played the games a lot of times, and for me the expansion became the greatest gift GOG has granted me. Yes, even though I paid for the game, I still really really appreciate GOG for giving me the opportunity.
But with that said, it does have some flaws. Mainly how it tries to make the game more challenging for the hardened Gothic fanbase. And although it succeeds, it doesn't feel very rewarding after the expansion, especially not for the newcomers. Also, the way scrolls are handled now is stupid and waaay too overpowered.
So instead, as a newcomer you should try the game without the expansion first. My suggestion is to play as Militia/Paladin if you're a newcomer; he never gets seriously powerful, but you'll finish the game with a strong foundation and with the easiest route.
Opinions?

I did play all the way through the first time with just Gothic 2, since that was the version I bought the first time.
And it was what sold me on the Gothic series (well until 3, 3 sucked).
In fact, I've yet to play through with the expansion. I bought the expansion, and started a game, but didn't finish.
And yeah, it's LOTS harder, IMO. The animals are MUCH tougher, and even though I'm way up in levels playing the expansion (well, last time I played that is. Been awhile. I purchased 1 here and am now in middle of that one), those T-Rex looking things (what are they called again????) are almost IMPOSSIBLE with the add-in. And those T-Rex looking things that breathe fire ARE IMPOSSIBLE, at least for me, right now.
But the entire world it opens up is so cool, (plus anything with Pirates is pretty cool. :) ), and the way it incorporates itself into the game so well, I dunno, I could see it both ways. Maybe for some it would be better to play it plain once and then with the add-in, but that might take some of the suspense out of the way the add-in fits in.
I dunno. It's a good question. I do know I agree with you on the whole magic thing though. It seems they set it up to make magic more necessary (by making the adversaries more difficult) and so the trade off was all spells cost 5 MP (or whatever, I think it was 5 LOL). Yeah, that seems just wrong to me. For this amazing, earth shattering spell to cost 5 mana as well as the simple provide light to cost 5 mana, just seems weird.
If the ending is different with the add-in, then by all means I would agree with you and say play it once straight and then again with the add-in. But if not (and I suspect it's not) then maybe the first time through with all the wonder of that new world added would be the best.
It's a good question though. I'm disappointed that I even played 2 before 1 now, because of how well the story in 2 followed 1. And the fact that 1 really is basically the same game as 2 (the jump in technology and the way the game appears and plays is really very little, certainly much less than I've seen in other sequals) makes me even sadder that I didn't find 1 first.
Still the best computer game I've ever played, IMO, as far as combat, storyline, immersion, and wide open playability. Just an awesome, awesome, awesome game. Well, after I configured my gamepad that is. LOL, I actually installed and tried it and quit out of frustration with the controls about 3 times before finally finding heaven with my gamepad.

If you played the original Gothic II first like I did you'll really appreciate the huge number of improvements and additions. NotR also resolves some of the unsolvable mysteries of the original, like why the bandits are out to get you, why there is a wrecked merchant caravan near Akil's farm, and so forth. The add-on world is especially rewarding, with some great locations and interesting new enemy types, and the addition of stone tablets throughout the island makes hunting for secrets even more rewarding than before.
The new LP-scaling system is vastly more difficult, but it means you can't easily max all your abilities. Under the original system I was able to max out my strength, two-handed and bow skills almost entirely through training, whereas with NotR you really need to use the tablets and other tricks once the LP cost multiplier start to get too high. The add-on world's enemies and overall greater monster population in the other areas means there are many more opportunities for gaining LPs.
The 5 MP cost only applies to scrolls, which was done so non-mages could still cast all the scrolls; runes have MP costs ranging from a mere 5 MP for simple spells right up to 150 MP for immensely damaging spells. There is still only a finite number of spell scrolls available, however (with the most damaging ones being especially rare), so the only way to regularly cast spells is to become a mage.
NotR doesn't change the ending; instead, the add-on world has its own ending. You can go between the worlds freely, but you must finish NotR's main quest before you can end Chapter 3.

I never implied that the magic was a problem; in fact I just think the way scrolls are handled makes the early game too easy with some of the summon scrolls.
And yes, I know. Having completed the game 6 times by now I know a few tricks ;)