Runaway trilogy and Black Mirror trilogy costs almost the same price at the current sale and I can buy only one of these series. Which one should I pick? I like horror stories as well as some comedy-crime adventures so this is a hard choice. According to you which games have better driven story, more interesting characters and better puzzles (or maybe some others crucial elements)?

I played both Runaway and Black Mirror series and found that both series had its Ups and Downs. If you have to choose I would suggest the Runaway series because of its better, in my opinion, story. Though, Black Mirror series is horror themed, and that's my favorite theme, the story is somewhat slow and sometimes not interesting. Gains points in atmosphere though!

(almost) spoiler free mood videos
Runaway
The Black Mirror

I own them all, but I have only played the first one from the Runaway series. Kind of meh, but I've played worse.

Luckily the second is even worse.
The third is okay though...

I haven't played Black Mirror series so I can't help you with this but about Runaway saga I've played the three games and they are great point & click adventures. They're full of humor, action, good songs, and very well writting characters.

The first one and overall the third are the best games in saga (the second part is enjoyable) so I recomend you give them a try.

Enjoy!