I am Looking for a seo software which can make my life easier .It is really a tough task nowadays to do the search engine optimization at home yourself itself even with the numerous amount of software available in market.
Why is there no one best ?
There are simple reasons behind this the work which these tools used to do are now available online.Even google and microsoft are providing tools which can help webmasters a lot rather than buying the same thing for money. If you leave some one or two functions i think all of the work which these software do can be done with various online tools and that too free and reliably.
You have three distinct features provided by google for keyword research
Go here
https://adwords.google.com/select/KeywordToolExternal
Provides you the greatest amount of related search quries than any other software online and offline

http://www.google.com/sktool
Search-based Keyword Tool : which allows you to get a keyword within the range of your website and bid amount.If you are publisher then you can select the high paying keywords from here.You can filter and incorporate them into AdWords.

With this tool you can compare search volume patterns across specific regions, categories, time frames.What people are currently searching for and what are future searching trends.
www.google.com/insights/search/

Hot trends – about what people are searching all over the world.Really good tool which don’t have any good subsitute till now.
www.google.com/trends
From Msn adlabs
There are five keyword research tool
Entity Association Graph : well this tool does’nt impressed me at all.However this tool provides a graphic view of the associations between entities by mining the co-occurrences of entities in search queries or search sessions. Such associations will be useful when creating query suggestions or analyzing user search patterns.
http://adlab.msn.com/Vnext/Entity-Association-Graph/
Keyword Forecast Software From Microsoft
http://adlab.msn.com/Keyword-Forecast/
It forecasts the impression count and predicts demographic distributions of keywords. Age and genders.Really good tool.

Keyword Group Detection — this tells you the related queries for a particular word.But i think this tool also is not as good as i was thinking.
http://adlab.msn.com/Keyword-Group-Detection/
Mutation Detection or common misspellings or alternative spellings searching tool.
http://adlab.msn.com/Keyword-Mutation-Detection/
Search Funnels
Customers often perform searches by typing related keywords in specific sequences. This tool helps in visualizing and analyzing the customers’ search sequences. For example, you can learn how many people search for dell and then search for bestbuy,gateway,ebay etc. Please enter a keyword and select options.
Estimating the high paying keyword software
https://adwords.google.com/select/TrafficEstimatorSandbox
you have to put in the keyword and select the country and then it will show you the search volume.Along with Estimated Avg. CPC Estimated Ad Positions Estimated Clicks / Day Estimated Cost / Day.
keyworddiscovery.com
Now this tool is really suggested by me
http://www.keyworddiscovery.com/search.html

i have used it and it works really good it provides you a set of important keyphrases which i think hardly any software do.It is from trellian.
Wonder wheel :
http://www.google.com/search?q=iphone&hl=en&sa=G&tbo=1&num=100&tbs=ww:1
This tool can also help you find some related keywords for a search for example we have taken iphone it shows following results.
Related queries : http://www.google.com/search?q=iphone&hl=en&sa=G&num=100&tbs=clue:1&tbo=1

It is also A good source to know about the related queries.