The "right on schedule":  So, you beat level 7 and you get an Achievement/Trophy. It's exactly what you expect right when you expect it. Awesome!

The "why didn't you warn me!?":  So, you just killed 100 koopas.  You didn't expect it (and eventually you were gonna do it anyway), but you get an Achievement/Trophy.  Awesome!

The "I need a strategy guide":  How in the hell was I supposed to know I'd get an Achievement/Trophy for falling into a manhole?  Who came up with this?  Oh, well.  Awesome!

Achievements/Trophies are awesome, but which is MOST awesome?

I'm not 100% sure what you mean by your definitions, but I like the kind where you have to kinda have to try and get them, but they aren't impossible. So a trophy for beat level x is sort of stupid. But a trophy for get x kills with weapon y is cool. I also like beat object x in y time.

Essentially, I like my trophies to be that extra little challenge.

I kinda like it when an Achievement just sneaks up and gooses me in the butt. It's great to get one when you aren't even trying to get one. I guess I'm a "why didn't you warn me?" kinda guy.

Also, I was in the middle of changing the names/descriptions when the thread posted (damn Enter button!). Hope the thread still makes sense.

I think the "level 7" ones are just lazy so I'll say a mixture of both A & C, I liked the "I'm on a boat" and "My brother is an Italian Plumber" trophies from Borderlands, that was quite creative I thought.

I hate missable achievements. I like to go through a game normally. I don't want to follow a guide to make sure that I get the missable achievements. If I miss the achievement, I miss the achievement. I'm not going to replay a game from start to finish just to pick up achievements I missed.
Definition for those that don't know what those are: http://www.giantbomb.com/missable-achievements/92-4261/

As for ideal achievement design, I think there should be some "right on schedule" achievement (say one for each chapter, act, stage or whatever and for beating the campaign) but the majority of the achievements should either be a challenge (without being a tedious grind. ie. 100,000 kills or collect X amount of Y object or open every treasure chest in the game. Gears of War, Crackdown and Lost Odyssey, I'm looking at all of you) or encourage different ways of playing the game, rewarding the end-user for experimentation and discovering something neat about the game. I do not like achievements with a grind-heavy sort of nature. Takes the fun out of the game.

That said, I'm not complaining when achievements come easy. lol. The gamerscore is nice. But in principle, in order for achievements to really mean something, the challenge and experimentation/exploration/hidden easter egg factor should come into play.

Ultimately I guess I'd say a mixture of all three, with more emphasis on "why didn't you warn me?" and "I need a strategy guide"

I'm kind of a fan of the ones you don't see coming, maybe because I unlocked my very first achievement by accidentally falling off of a shelf in Dead Rising.

i hate the trophies where "i need a guide"

my vote goes to "why didn't you warn me"

I like the ones that reward you for sucking. There was one in LotR: BFME II. Where you got it when you lost to someone 20 levels below you. xD

The ones you get for beating a boss.

All I'm gonna say is that I like my achievements like I like my sex, unsuspecting and with the strong arm of a manly man to hold me down.