Now, this topic is really a can of worms...

But I'll try to give a short description from my point of view of some sticks.
Cougar Hotas
I have no experience with this stick, but from what I hear, the vanilla stick is
nothing short of crap... You will need to purchase expensive mod-packs and
install them yourself to turn the stick into something usable.
Saitek x52(standard)
I used this stick for about 2 years and it is, in my opinion, awesome.
It seems to me, that the main reason some people dislike the x52, is
because of it's sloppy springs. But imo, the springs were just perfect.
I did have some problems with the stick occasionally resetting mid-flight,
which often meant I would fall out of formation or even crash if it happened
during take-off or flare. Make sure you have the stick replaced at the first
sight of such problems and an x52 will serve you well at a reasonable cost.
Caution: With this stick, you will never have to touch the keyboard again,
something that there is no going back to after getting used to the x52.
Logitech G940
Plenty of buttons, (just like the x52), plus force feedback stick. Since it is
force feedback you can set the return-to-center spring as loose as you like.
The pedals, although a tad narrow, are smooth as silk.
Downsides:
Expensive, but worth it if you have the money to spare. Then again, it's not
a lot more expensive than purchasing an x52 + pedals. (Which is a very viable
option...)
Unfortunately Logitech still have a few quirks to work out with this setup.
Primarely the so called "Reversal Bug"(google it). Logitech has finally managed
to produce a firmware fix for the stick-X/Y which decimates the "reversal-bug",
but the bug still remains on all other analogues.
So, it comes down to what you need your stick to do.
- HOTAS? (x52 or G940)
- Pedals? (x52+Pedals, or G940)
- Force feedback? (G940 or find a MSSWII on ebay)
Another thought, if you do not have a TrackIR(
www.natural-point.com), I would
definitely go with a cheaper stick(like a Saitek Cyborg, MSSidewinderII) and get
one of those head-trackers first. I don't think there is a disappointed trackIR
customer out there...

)
Good luck with your choice!