I prefer to use google analytics because it provides all the basic information of our website.it shows most visited pages,which user is active now on our site as well as his/her location and source medium,total sessions,how many clicks we get on particular pages and bounce rate, the user behavior after visiting our site and much more.
The second best tool is google webmaster tool,provides information on HTML errors,internal links as well as backlinks of sites,crawl errors and much more.it also allows checking robots.txt file.
Also, we can use keyword planner for keyword research,SERPs SEO extension for check rank number of site on the search index,senseo to check all the meta,h1 and title tag information.