Luckily managed to buy the 6 start package twice... Yahoo... Now I'm in dilemma on whom to upgrade to 6 star. Kindly advice me sifus.

I have

Venom - 6 stars
Hulk - 5 stars
Hulkbuster - 5 stars
Spiderman - 5 stars
Ms Marvel - 5 stars
Ultron - 4 stars
Ironman - 4 stars
Red Hulk - 4 stars
She Hulk - 4 stars
Modok - 4 stars
Vision - 4 stars
Black Widow - 4 stars
Yellow Jacket - 3 stars
Captain America - 3 stars
Deathlok - 3 stars
Black Panther - 3 stars
Antman - 3 stars
Ghost Rider - 3 stars
Giantman - 3 stars
Thor - 3 stars
Falcon - 2 stars
Singularity - 2 stars
Iron Patriot - 2 stars
Superior Spidey - 2 stars

Referring to the ones i highlighted in red bro,
http://imgur.com/LaFLJ9N

It's better to change the Physical attack by lvl % value, to a flat value like Physical attack +107 (as like your 5th stat option)
Taking for example your Elektra is lvl 57, your last stat option as per image above is Physical attack by lvl 50.8% which would roughly be a flat value of Physical attack +28 after conversion (Elektra lvl * Physical attack by lvl %/ 100)
For that gear option that you can change to, you should be able to change the option to Physical/All attack +130 to 150 instead of Physical attack by lvl 50.8% which only gives you Physical attack+28 (currently @ lvl 57) or Physical attack +30 when your Elektra reaches lvl 60.

Just an example of how most of us setup our gear stats
http://imgur.com/8EWSDze

Care to show your Elektra ISO set page? You should be able to roll (change set) for an 8 set ISO even if you have yet to reach it's lvl requirement.
A sample of how it should look like
http://imgur.com/CtDpFl9
Each try of change of ISO set will cost you 10k of gold and the set you get will be random just like how you change your gear stats option.
And the bonus % from the ISO set will vary depending on your average ISO level.

Hopefully this clarifies a little on how gear option works