The Broken Sword games, the Monkey Island games are all fun.

The Black Mirror series (1-3, not the most recent one), i really liked the mood and story the puzzles were mostly pretty easy. The first one hasn't aged too well, especially the slow movement speed of the player character can be annoying but its still worth playing id say.

The Deponia Series wasn't too hard either, with some nice (dark at times) humour and story twists. I don't know how well the translation is done though, could be that they loose some of their appeal if not played in german.

All the Artifex Mundi games here are easy and relaxing.

I found "The Next BIG Thing" to be pretty easy.

I solved probably 80% of the puzzles completely on my own.

Another 10% I solved using the in-game hint system, which gives you more & better clues the more times you use it in a row, when you get stuck.

The final 10% I looked up the solutions on the internet.

I spent about 8.5 hours with it from start to finish, but I've heard of other people beating it in around 6 hours. I'd say it's mostly easy, but with a few hard puzzles.

It's worth playing if you like adventure games.

Easiest adventure game for me was a Full Throttle.

The Darkside Detective is a collection of 9x short episodes which were fairly simple.

Last Door Season 1

(Assuming you aren't going for 100% achievements)

Last Door Season 2 misses the cut.
There was one instance where I was forced to resort to a walkthrough. (The press-the-regions-on-the-map-that-correspond-to-a-story-puzzle)

Again, if I cared about achievements I would have been forced to use a walkthrough to get them. One of them is click on something which starts a timer to run to a different area and pick up something. You aren't told where to run to though, and there is no way to retry the event without restarting the game.

I recommend The Cat Lady and Downfall.

I second this opinion. If you like Poe-esque and Lovecraftian inspired narratives, give it a try.

I'll add:
Grim Fandango
Fran Bow (scary, fantastic)
Gemini Rue (cyberpunk)
Kathy Rain (thriller)
The Lion's Song

I had trouble with Grim Fandango. The "hotspot" indicator is represented by the protagonist turning his head in the direction of something that can be interacted with.

For most of the game I was too stupid to notice such subtleties.

That being said, now that you know to look out for it, you will have a easier time.

I have played Pajama Sam 1-3, however I haven't played the GOG versions of 2 and 3.

Syberia 2 seriously? Crazy obscure puzzles in that...

Blade Runner is really easy as it doesn't require use of items for puzzles, rather having them in inventory.

That's one of these "impossible to answer" questions, because everyone will have a different opinion of what constitutes as "easy".
I'm with Ancient-Red-Dragon that "The Next Big Thing" was fairly easy - though you may come to a different conclusion.

I'm also with koima57 that "Syberia 2" has some obscure puzzles - and yet, you may think differently, seeing that you list it as one of the "easy" games you played.

And that goes for just about every single adventure game out there: what one player may find easy (maybe even too easy), will be an impossible-to-crack tough nut for another player.

I recommend Tormentum: Dark Sorrow.
Are You looking for:
Quite easy puzzle?
Two diffrent endings?
Atmospheric artstyle?
Imprisonment in pugnatory?
If You answered positively on above questions, Torentum is a game You are looking for.