Dragon Force (Fairy Tail) or Super Saiyan (Dragon Ball Z)

I personally prefer Dragon Force over Super Saiyan. Admittedly, Dragon Force cannot destroy planets, but I see it as more special because you see Super Saiyan used in just about EVERY fight, big or small, after Goku fights Frieza, and they need the extra boost in order to win the fight. On the other hand, you see Dragon Force used only six times in the show thus far (I've counted), and when you do see it, you know it will be an awesome fight; on top of all that, Dragon Slayers don't need Dragon Force in order to win, Natsu and Gajeel vs Sting and Rouge proves this fact.

Dragon Force seems not as op after Natsu single handily destroyed Sting and Rouge, that being said I am not a Dragon Ball Z fan so ill go with Dragon Force

math basis: Theory DBZ Powerlvl and FairyTail mentions

Dragon Force is said to amplify the power of a human to the level that can slay dragon's
along with speed, battle sense and attack calculation prediction, extremly amplified.

Human Power : 5
natsu's possibly around 30 when sleeping
Natsu Pre-timeskip when fighting for friends 20,000 give or take
Natsu Post-Timeskip during the GMG over 50,000 easily
Dragon Power 40,000


Super saiyan multiplies the power of the user by 50x show here

http://dragonball.neoseeker.com/wiki/Official%20Power%20Levels

Conclusion.

Dragon Force is the Better Form Change

Dragon Force overall amplification is far greater then Super Saiyan.
Dragon Force is Rarer as only seen used by twice Natsu via eating highly powerful magic substances

and the 3rd generation Dragon Slayers Sting and Rogue via Will Power

Laxus's Dragon Force was a false dragon force
Gajeel's scales are not Dragon force but a skin transformation
Cobra never went Dragon Force, rather a skin transformation intead

Dragon Force overall amplification is far greater then Super Saiyan.
Wait but you just said Super Saiyan Transformation multiply their power by 50, and According to you Dragon force would only increase Natsu's power by 2 times before the time gap, wouldn't that mean Super Saiyan transformation would be 25 times more amplified?
Also it seemed like Sting and Rouge could go into Dragon Force whenever they pleased.

Dragon Force is said to amplify the power of a human to the level that can slay dragon's
did you read the full post

Also your numbers are terribly wrond since it only takes >1000 power level to blow up the moon (Shown by piccolo, did it one handed as well.) And Natsu is unable to even closely blow up the moon so....