Your view on this is wrong.
Gmail is secure as fuck even though it's VERY popular - the only viable weakness is your password strength.
I am using gmail for a very, very long time and will continue to use it (mostly because of the great service and being able to use the IMAP protocol with thunderbird) and it has a great spam protection.
Yahoo mail was great in it's time... many years ago. Now it's just crappy email system.
Hotmail?... pff yeah right.
This view (more popular -> more likely to get hacked) does not apply to gmail in terms of server compromisation. They can only get in if your password is very weak.
Dont get me wrong, i never talked about gmail Is poor securety.I like gmail too, but its popularity makes me worryed. There are posts all over the web on how to hack gmail, books only based on how gmail works, how to take it apart, and how to use it for yourself, There are tools that script kiddeys can use to get gmail passwords. Thats why im saying gmail is secure for a short time. Becaus people are always trying to hack it.
NOW i would say gmail is secure only if
MY PASSWORD(Demo similler to my own) :
IS STRONG ENOUGH TO PROTECT MY DATA FROM posted methods of hacking gmail/methods taught in books/gmail hacking tools.
Note ABOUT MY PASSWORD : FOR making a strong password i choose a long sentence then put special chaseaters like * insted of "o" , $ insted of "S", : or / betwen every words and then put numbers betwen every chaseaters. I use a phone number or sl number for making it easey to remember the password like shown above.
And the only thing that bugs me about using populer Services is that there are alot of people out there alwyes trying to hack the system.
MY POINT : More popularaty, more want of it to be hacked.