Honestly, they're all good in their own way. Some are exceedingly blunt, but that's because sometimes one needs to be exceedingly blunt to get through a writer's thick skull/ego. Some are extremely meticulous and thorough with their critiques — I'm one of these folks. If I see something with an egregious number of things done poorly, I do a line-by-line. Others are more big picture, is this unique/has it been done before/etc.
And within those (and other categories I did not mention), everyone is biased to a point by what they look for in an article or tale. Some people look for something outright weird, some are looking for a deep backstory, some are looking for just a hint of one, and some are looking for that emotional hit. All of us are looking for something that interests us, and interest is subjective by nature.
Most of us, however, if not all of us, are a massively confusing mixture of everything above and more. So it is pretty potluck.
That said, we are also looking for proper formatting, good grammar/grasp of the English language, overall coherency in structure, structure in general, competent writing, and other elements of decent writing skills.
We're all going to be blunt when the occasion calls for it. If the idea is bad, we will say it is bad. I've had that happen to me more than once.
All of us are giving the best critiques we can, its just that your idea of a good critique and that of your critic may be vastly different. I give line-by-lines because I've found them to be highly useful and full of information. But I've also given brief summaries of what is wrong with something when there is so much wrong with something that a full critique would take several hours. And I know there are others wayyy more experienced than I that do the same.
All of the veteran writers here are, well, veteran because they are very, very good. Djoric and Dmatix do some of the best tale work I can think of off the top of my head. CryogenChaos does some great work too. Randomini is a new guy, but he's done a lot of good tales in the brief time he's been here. I'm not saying he should be your go to critic, but you may consider him. Aelanna, FortuneFavorsBold, and others do line-by-lines that are exquisitely detailed. Roget, thedeadlymoose, Accelerando, Zyn, VincentRedgrave, Clef, Bright, they all give good critique, though Roget, Clef, Bright, and moose, as busy as they are, are hard to get ahold of sometimes. I've gotten good advice from Tox and from TuomeyTombstone. Everyone here will give you solid advice, as will those SS/Mods/Admins who I've not mentioned, and I'm sorry if I forgot you/didn't mention you. Additionally, I know some of the folks mentioned aren't SS/Mods/Admins, but they are veteran writers. Trust them.
Hope this helps!