Out of all of those, I would be most interested in playing The Mermaid Mask, since it is already on my list of games to play.
I don't know about Shivers, how much old games junk is in it?
I will pass on Perfect Tides as it doesn't seem to be a game I would enjoy, and I haven't played the prequel.
Phantom Fellows - no, and I won't elaborate further.

I would suggest notpron.com. The self proclaimed hardest riddles on the internet. It's free, and it has a perfect structure for community playthrough. But I don't know if anyone is interested in playing (really) hard games.
As a more casual alternative, there's Desktop Explorer, which is quite similar and very fun. I'm at the 1/3 point in the game.

Two on the Mermaid Mask!

Heya posters and lurkers, great chance to get involved. Play and discuss a current release! You get Joe's wit to boot.

I would be interested in playing a classic style P'n'C with story and characters, old or new, like Dragonsphere or Kathy Rain (maybe Flight of the Amazon Queen, since it's freeware now).

Unfortunately, the only game on the list close enough is The Phantom Fellows and its visual style is a big turn off for me.

We can add one or more of those to the list.

@Joe: I thought twice before looking into that link, but it's a legit game and I'm adding it to the list.

I like that you thought I was going to play a prank on you with this link.
I didn't realise I had a reputation as a trickster around here

Put me down for Mermaid Mask!

Great! Glad to have you on board!

Alright, after reading the review, I'm throwing Endacopia into the mix.

Suggestions are still welcome! 

Right now, Mermaid Mask has the most traction.

Endacopia is pretty cool game, but it's not a point and click game.

Alright, after reading the review, I'm throwing Endacopia into the mix.

Now that I have read the review too, it suddenly looks like a solid contender for the adventure game of the year.

Of course, to affirm this, I have to play it first.

Not sure if it's a good candidate for a CPT though. The review says that the game has a lot of player freedom, which could be disorienting to the flow of CPT.