My favourites from the first 10 pages:

CivCity Rome

Heroes of Might and Magic IV, where the heroes can actually enter the fray of battle, unlike all other games in the series

There's a wide variety of games amidst that 34-page list I could recommend, but the thing is, we probably all like different things. What's appealing for some people, might not appeal to others.

My best tip? Wishlist what takes your fancy, then keep an eye on sales to get them at reduced cost.

I'll make it easy for you: Buy Thief Gold

There, no burden of choice. No nonsense. Just pure, 100% Thief Gold bliss! Thank me later.

Obviously I'm going to shill for Pajama Sam Vol. 1, but tbh you're better off waiting for a sale (it usually gets down to $4) because the two games worth playing of the three are admittedly short. Vol. 2 only has one game worth getting imo, You are What you Eat, so that is an almost wait-for-sale.

Postal 2 is surreal fun but it often gets down to $1 (more often on Steam than GOG, too; and the devs seem to have issues with GOG compared to Steam)

Of the games I own I'll go with Beyond Good and Evil, SiN Gold, Jedi Academy (currently on Sale), Tron 2 (also on sale)

Also did you know that Guns Gore and Cannoli is less than 10 euros ?

Just get the 6th game on the list, Star Wars Knights Of The Old Republic. And when you're done. come back again :) (spoiler: it will be SHOGO)

Waifu puzzler HuniePop. Definitely. No doubt. ;)

Besides my joke answer:
The Longest Journey - Still my favorite p'n'c adventure to this day. It's too bad the sequels just didn't live up to the original.
Crusader: No Remorse - The keyboard-only controls take a bit getting used to, but it's still a fantastic, bombastic action game.
Prince of Persia: The Sands of Time - The best in the franchise (before Emo Within or Arabian Nathan Drake).
FlatOut 2 - One of the most fun arcade racers around.

All of these, with very few exceptions:

http://www.gog.com/games?sort=popularity&page=1&price=u10&category=adventure

EDIT: OK, apparently category doesn't work as a link.
Anyway, most of the adventures on that list are worth buying, and the ones that are not, are mostly games in a wrong category (not really adventures).

Divine Ragequit? No, please don`t buy this crap!

You must have appalling taste. :D

1,200+ titles at less than 10 bucks?

Man, what a time to be a gamer.