Good stick to buy:
That very much depends on what you can/are willing to spend money wise.
What you definitly NEED is this:
8-way hatswitch
throttle lever
rudder control (twisty or rocker rudder)
as many buttons as you can get.
In the price range to 50 EUR, there are a few good sticks like the Saitek ST290 Pro or Saitek Evo, both being twisty rudder control (ie you need to twist the stick handle for rudder input). I myself used a Speedlink Black Widow (rocker rudder!) for over a year and with much success. Another good one low price are the Saitek Evo (twisty) and the Thrustmaster afterbutner II (can do both, twisty or rocker).
If you know youll stick with the game for a while, and can afford it, go for a Saitek X45 (rather stiff springs, rocker rudder) or a Saitek X52 (twisty and pretty loose springs). Those, combined with a set of rudder pedals, are fully HOTAS (ie you do not need to remove your hands from stick while fighting). They will cost you (without peds) about 100-130 EUR.
The top notch best thats out there is CH products. Joystick, throttle and pedals will cost you around 350-400 EUR. Those will last a lifetime though. This is something id only buy if youre sure youre going to be in the flight sim "business" for a while.
I started out with a 10 EUR stick (small throttle, no rudder, 5 buttons) - which was completely useless. Even before my free trial was out, i bought the Speedlink stick.... which was a very good deal for the money and got me a long way. In the long run, i needed more buttons for finer and quicker control in fights (no need to remove hand from stick to drop flaps etc) - im now on a X45 and CH pedals, that one by one will be replaced with CH stuff as they go out.
What you buy is kind of a personal preference. If you can do it, go to a media store and take a few sticks in your hands - see which one fits into your hands well. Youll also need to decide if you like twisty or rocker rudder better. Then google for the sticks and try to find a good deal on the web. Comparing prices can really pay off. Id be vary of used sticks from EBay - even if they are looking good and new on the outside, you cant see inside.... its usually not worth the reduced price. If you get new, youll always have a warranty.
Whatever you buy, stay away from logitech joysticks. They have a pretty low quality at the moment and usually only last a few months.
I hope this helps you a bit,