I should post the answer as a comment to Phil B.'s post, but since it contains some useful content for the others, it will also be an answer.

First of all Phil B. thanks for the link, that's exactly what i was looking for and i will mark it as an accepted answer.

After reading the PDF, here is the summary of which blocks can we risk buying and which to avoid.



**Best ones:**

Company (average score)


- Lego (99) - obviously - http://amzn.to/1NcybMJ
- Gudi (99) - http://bit.ly/1hCKxCp
- Star Diamond (99) - http://bit.ly/1Gd5Mq7
- Lite-Up Bricks (97) - this one are interesting, bring Led lighting powered by USB port. - http://bit.ly/1GH5K4Q
- Click Brick (93) - not produced anymore
- Oxford Toys / Kre-o (90) - http://hasb.ro/1jodMec
- Cobi (87) - http://amzn.to/1jyUFxs

**Worst ones:**

- XQL (14)
- PMS International (14)
- Yixing (?) (5)
- SY (0)
- LELE (-79) - I don't know how did they come below 0, but they did it. - http://bit.ly/1VQOt00

Thanks for checking the list