Is really URL with variables no SEO friendly ?

Yes, URL with variables no SEO friendly.

These type url's are not seo friendly, i think so

These types of urls are not SEO friendly.
Search Engine understand the static url very clearly.

With the latest Algorithm updates urls with variables are not user friendly.

Yes, the URLs are not SEO friendly, if it is auto generating, then these can be handled using canonical tags

It is best to use keywords or maybe what the page about as long as there's no special character.

Yes, this URL is not SEO friendly

The url with variable and query string is not user friendly because it is does not maintain hierarchy with broader categories to the left and more specific categories to the right. But user url without query string is count as user friendly because it is maintain hierarchy with broader categories to the left and more specific categories to the right.

YES I WILL GO WITH GK&NP BOTH ARE RIGHT

Bom na minha opinião é bom prevenir

Ya Ya Ya Ya Because usage of unique characters in URL barrier for crawlers so best method to prevent it.

Yes...Because use of special characters in URL barrier for crawlers so best way to avoid it.

I know , everybody just say "no SEO friendly", but who checked SERP for domain.xxx/?variable and domain.xxx/variable and compare results ?
My question is based on many say no SEO friendly and discourage the utilization of CGI variables, but at some time I did tested with same HTML in both forms and even variables version got higher position in Google.

Yes it is not seo friendly at all

Yes. These type url's are not seo friendly...