Wow, thank you all very much for your detailed replies!
When I understand the gist of your replies, I'll probably soon want better eyepieces and diagonals. So I will consider that when choosing a telescope.
Tele Vue or Pentax are definitely out of my planned budget, which I should have told you in the beginning. I'll intend to spend about 500 to 1000 Euros, not necessarily all at once. I'd love to grow step by step to better understand what each part of equipment brings. And I'm just looking for visual equipment. (I've already started doing some AP, but for now I just use my DSLR with an old 50mm 1,7 lens and a photo tripod. I'm impressed what's possible with this simple equipment even without any guiding.)
BST Starguider are often recommended, but none of the big telescope shops in Germany seem to sell them. And there are even no offers from german Ebay users. The Baader Hyperion get recommended for users with glasses. At least I've seen the recommendation on several occasions now. So, I'll have to calculate about 150 Euro for a decent eyepiece.
(Regarding the OTA I'm gonna choose one day: I'm still torn between best performance and portability. But as I have a lot of things to research and to ask, I'll open a dedicated thread later.)