Dajka Botond:
Thank you all for the suggestions! To clarify I want to use the telescope for visual astronomy and then maybe get into astrophotography.
A Dobsonian is probably the cheapest, most practical and intuitive way into visual astronomy. A 6 inch provides good views of a range of deepsky objects as well as the moon and planets.
If your intention is to just try some imaging out in a simple and easy way then a good option would be a goto dobsonian. This is not suitable for long exposures but works just fine for planets, the moon and even deepsky stuff up to 15 min or so --- which is ample to show galaxies and nebulae etc which are not visible visually.
I started both visual and electronic astronomy with a dob and was more than happy with that set up.
Tim