Sacred Haven of Debauchery

When I first launched G1, I spent half an hour trying to figure out its controls. Until I accidentally understood it.

Oh yeah, the second Gothic... I can't say the level offhand, but it's really easier for a mage because he actually arrives there as a mage, not some militia member (I haven't played as a mercenary, I don't know). And, in my opinion, it's easier for a mage to kill dragons - the "summon skeleton" rune, and that's it :)

It's definitely harder for a mage at the beginning of the game. If the paladin and mercenary develop combat skills, melee and ranged combat with physical weapons, then the mage needs to level up mana and accumulate enough experience to create runes. And at the beginning of the game, he will be without runes, only with scrolls, and at the beginning of the game, as a rule, there is little money to buy them, the hero is weak to wander around "rich" crypts and caves. So the mage has to kill creatures in melee combat. But then, yes, he will become stronger.
Although in the first Gothic, when I was developing a mage, I managed to buy 30 "fire arrow" scrolls every couple of days and went around killing everyone, occasionally resorting to melee combat.
And I almost don't use summons at all. A skeleton doesn't kill a dragon. Not one, not twenty, I tried. But, after transforming into an Ogre, dragons are easily killed.

He doesn't understand anything. I think paladins are decent guys who respect the Emperor's commandments, and mercenaries are thugs and riffraff.

They're all thugs there. Mercenaries are former prisoners in the Colony. The former General Lee, who was framed and exiled to the Colony, is at their head; he's not a thug, and he wants revenge. Paladins, on the other hand, are arrogant and take advantage of the fact that they are the law. Well, these are also thug paladins, and there seem to be decent people at their head.
And there's one unpleasant blackmailer in the monastery, but otherwise, they're all nice ^_^

But on the other hand, paladin armor will be cooler than a red robe...

I like the cute dragon armor of the last level the most. And in general, it's also interesting to play as a mercenary. Although mages will be more original than paladins and mercenaries.

I once installed it with the add-on, and I thought I'd go with the mages (water), or maybe I didn't think about it, I don't know... in general, I wanted to play, and there are also pirates there. But I didn't play it.
If I had it now, I might go with the bandits. I don't really want to play as a mage; I've already played enough in NWN.
And I prefer playing in the third person, shooting from a bow.

There are only three guilds there (Fire mages, mercenaries, and paladins). There are add-on pirates, bandits, and water mages, but you can't join them "officially," in their guild, i.e., you won't get a water robe (although you can get pirate and bandit ones). And in the profile, it will only say fire mage/paladin/mercenary. The add-on ones are secondary, and you need to play as everyone at once in the main quest.