As someone who has xboxachievements.com as his homepage, I am a big fan of the idea behind achievements/platinums, though some can be really annoying. Mainly, the multiplayer ones. I don't even mind the grinding achievements, but mp achievements, especially the ones that require teamwork, are a pain in my rear 
I posted in the other thread about 100% completions, but I think I'm at around 62 plats/100% achievement games. Of course, my Xbox 360 shows 87 completed, but its including games that have added dlc since I last played them.
As far as my most proud, that would be between 2 EXTREMELY GRINDY achievements.
Proudest single achievement would be Gears of War 3 - Seriously 3.0 (I don't know the exact number of hours, but its easily 1000+ and 1 console's life)
Proudest 100% would be Star Ocean: The Last Hope (right around 650 hours on my save files, although I did miss a single treasure chest halfway through my initial playthrough and had to start a new game to get it).
Currently working on Titanfall (both on 360 and One), though I don't really consider it work as I love the game.
Needless to say, I'm definitely a fan of achievements.
That's awesome, but I definitely don't have the attention span to play one game that long. My most hours played games last gen would be stuff like Xenoblade & Skyrim, with around 130 hours (give or take) each. Granted, as much as I loved Xenoblade I probably would have played it even more if it had trophies. 
From your list in the other thread, I'm curious - as a huge PSO fan who *hated* PSU - how long did that 100% take you?? 
PSU didn't take long at all honestly. The original 1000 points were literally just story-related achievements.
The remaining 250 was for killing bosses in the online expansion pack (which required a subscription as well). Thankfully, they did a weekend event where anyone could fight the bosses (instead of having really high level requirements that would have taken 90 hours or so), so I signed up for a couple days and had some high levels run me through the boss fights really quick.
I think the online component is officially shut down at this point; if so, the dlc can't be completed. But the first 1000 is simple enough - just beat the game. I don't recall the length, but its probably 10-15 hours at most.
I'm sure I've put that much time into Skyrim, but as someone who isn't a big fan of Vampires/Werewolves, I haven't bothered with those achievements yet. I also have Xenoblade sitting on a shelf, waiting to be played. SOOO many backlogged games, especially when I spend so much time trying to complete all the achievements in them lol
