If you're a master gamer like me then all trophies are easy , jk.

I got Transistor on PS+ last month and while I'm still casually playing through it, most of the trophies are really easy. You just have to play the game and complete things. I'm not going to do them all (I can't be arsed with the limiter ones) but I'm about done with everything else. It's a fun game and easy too. (I'm finding it easy, never had a game over).

Also, dragon age games (if you are willing to put in the time)
Tekken 6 and Tekken 6 are piss easy.
Minecraft too.

I'm a weird one with Trophies, I think they are pointless but I do sometimes go out of my way to get them. Although I do wish they didn't exist and instead we had like in game rewards instead. Taking Transistor as example, complete all of a certain thing and get a skin for the character.

Oh, I don't know how long it took me, but I remember it to be pretty easy. The only thing that needs a little grind are the 100 online matches. But as the game is really fun, it ain't too bad imo. I even played it some more after I got the platinum. Are the servers still up? Might play that sucker again. 

But other than that, it's really easy as can be. Especially the solo part, it't the easiest Killzone ever. Killzone 2 (where I also got the platinum, btw ^^) is a hell of a lot harder! And the online trophies on Killzone 2 are just INSANE! Really, Mercenary is a joke compared to that.

The 100 online matches was the longest trophy? Hehe, I just leaved my Playstation Vita on with Killzone Mercenary in Multiplayer when I was at work. Got it after 2 days. The longest trophy was the trophy where you should kill 10,000 enemies imo! 

And servers are still up. 

Grim Fandango... the most annoying is the "tank control" trophy (the new stick control is a great improvement), but if you play it on the Vita, it's not so bad... the touch controls work great and you only have to use the sticks in a few cases.

The Order 1886

Is Home still up and running? I was under the impression that that was shut down months ago.

Back To The Future game and Pacman DX are real easy games. Tip: If you get the BTTF digital game, and buy the physical copy. The trophies are done different. So PSN treats the physical as a new set.

If you're looking for crappy shovelware games that take 4-10 hours to platinum here they are.

The Smurfs 2
Terminator Salvation
Toy Story Mania
Puss in Boots
Hannah Montannah
MegaMind Ultimate Showdown
Cloudy With a Chance Of Meatballs
NCIS
Magus

Up till the end of March. Only 1 Trophy is impossible for Home newbs. 50 log in days, which I'll miss.