Here are the few PSN games I have already:

The Walking Dead, Flower, Fat Princess, Worms, PixelJunk Monster and Shooter, Dead Nation, Wipeout HD, The Tales of Monkey Island, Tumble, Hot Shots Golf, Risk: Factions, and some others.

What I've had in mind and never played:

Journey, Final Fantasy Tactics, The Cave, or Bully (one of my favorite PS2 games).

Any other suggestions? I'd be interested in RPG recommendations or unique games.

Journey.

If you don't have PS+, get that.

If you already have PS+ The Unfinished Swan and a bunch of other games are on sale right now, check that stuff out.

If you liked Flower, get Journey, otherwise wait for it to go on sale.

I'm playing through The Cave right now, it's not bad, less adventure and more platforming than I expected but I'm enjoying it so far.

I would agree with Journey.

Demons Souls just came out (in europe at least) for 20

@Kidavenger Thanks for the post.

BABYBABYBABYBABY Persona 3: FES.
 
Or ff tactics as you suggested.

Get Journey. PEERPRESSUREDOITBUYJOURNEY.
PS+ is also a really good deal, but only if you plan to maintain it or are going to play a bunch of games really quickly.

Tokyo Jungle?

Okami HD.

JOURNEY!

And Unfinished Swan is currently $3.75 for PS+ users. $7.50 for regular folk. You may want to check that out.

Two PSX classics called Vanguard Bandits and Front Mission 3. Both are on my favourite games of all time list. Last I checked they were $9.99 and you can play them on PS3/PSP/Vita.