Both are good to get backlink but the more important point is that link should be related to your niche.

Wordpress is better because you can easy post your link, on blogger sometimes you need to login and register.
You have some nice plugins for fast commenting on firefox.

Thanks you all guys to help me

I think wordpress is better than blogger, because you there is no difficulty to add comment in wordpress but blogger has some.

wordpress is better its more popular and is more likely to have more viewers

Either of the two as long as it's do follow.

Both of them are good for commenting its depend on the reputation of a site you commenting.

I like wordpress

It is easier to expose your website on WP than on blogger, I search for wordpress blogs also for comments..