Hi are you looking for top seo provider to purchase SEO service .Then here i guide you with the point to be watched while choosing a SEO service provider .They are
1.Look in forums for feedback about customers who use their SEO service .
2.Google the company name
3.Ask for examples of sites they have optimized.
4.Check the PR of their own site.
5.Don't trust any company that is offering guaranteed position 1 results for your target keywords. SEO is unpredictable and cannot be directly controlled, only influenced by certain factors, therefore noone is able to guarantee you certain positions.
I kept this thing in my mind and choose one among the best SEO service from XnYnZ.com
here they are providing search engine visibility service which helps to bring traffic to our site .They provide us with Powerful reports that shows how to move our website up in search results.