This all boils down to one thing .... How You Like to use your mail ID, How basically you would like to manage it.
For example , if you are sticky on using Mail Clients to get read and reply to mails then you need to choose you mail id with a provider that will give you every possible ways to use it on your Mail Clients.
From Folders sync support to calendar support etc ( to name a few )
Also many people use multiple computers and may like to have their mail come in automatically in each computer in a very organized manner.
Gmail does tops up the list for all this, since it still uses IMAP to sync.
So, WebDev and other POP may not be supported by your mail clients, so choosing the best ID for your particular use depends on yourself.
As far as the service quality provided by this FREE email providers are mostly similar and good.
Hotmail is very good since it integrates with MS Office ( read skydrive ) and also is now very fast to use.