So both Anime made by the same guys , they were directed and wrote by the same people  ( Hiroyuki Imaishi and Kazuki Nakashima ),

Both Anime has the same color presentation, art and type of pace. Both Plot has the same similarity. 

Both are getting critical  aclaimme on western audience, both Anime are epic

So which One is better ?

GURREN LAGANN 

Epic Scene ( Beware light Spoiler content)

<iframe width="560" height="315" src="https://www.youtube.com/embed/kVg7ACy7-yQ" frameborder="0" allowfullscreen></iframe>

Finak Battle Scene (Beware heavy spoiler content )

<iframe width="560" height="315" src="https://www.youtube.com/embed/U9N-BuufhyU" frameborder="0" allowfullscreen></iframe>

Opening Song

<iframe width="560" height="315" src="https://www.youtube.com/embed/ok295z8vU3Q" frameborder="0" allowfullscreen></iframe>

                                                                                                                  OR

KILL LA KILL

Epic Scene (Beware light spoiler content )

<iframe width="560" height="315" src="https://www.youtube.com/embed/T4NBsNIH57Y" frameborder="0" allowfullscreen></iframe>

Final Battle (Beware heavy spoiler content) 

<iframe width="560" height="315" src="https://www.youtube.com/embed/T4NBsNIH57Y" frameborder="0" allowfullscreen></iframe>

Opening Song

<iframe width="560" height="315" src="https://www.youtube.com/embed/K42ED-7PWAo" frameborder="0" allowfullscreen></iframe>

So Acording to your opinion which one is more epic and which one is better?

For me i choose Gurren Lagan, my reason are , first i am mecha lover, or robot lover, and although Kill la Kill has better OST by Hirano Sawayuki Kill La Kill just too short and have a less adventure type plot for a guy like me. Both has a lovable character but Gurren lagan has more charm and unforgettable character . And also Gurren lagan story is more sad and tragic and if i can count it has more sad and more dying character then kill La Kill.

But both Anime are my favorite Anime's

Easily Gurren Lagaan for me personally.

Gurren Lagan! Row, row, fight the power!! Better characters, universe and story.

I like Gurren Lagaan. Apart from all the awesome stuff like the story and etc, I specially like Yoko's character design. She looks soo awesome T_T

For me its Gurren Lagann.

I watched both. Loved both. Kill La Kill was by no means bad, in fact, it was pretty outstanding, but Gurren Lagann's message (Drill = Will, your is capable of piercing the heavens) was executed far better than the "Don't lose your way" message Kill la Kill presents. Another things TTGL did far better than KlK was the final battle, which was nuts epic, but not only epic, "galaxy being used as shurikens" epic, and KlK didn't manage to top that although it was pretty good on its own right. Also Kamina.

Mako is among my all-time favorite sidekicks, though. The series wouldn't have been the same without her at all, so there's that for Kill la Kill.

Gurren Lagan is probably the most epic thing I've ever seen. The entire premise, of mankind rising up from hiding in the dirt to wielding power that shakes the stars, is amazing.

It also had one of the most powerful turning point scenes I've ever seen in visual media. It was a fun little adventure until around episode 8, then it just fucking blows up everything you know and becomes something visceral.

TTGL is one of the greatest anime of all time and a master class in plot escalation, while KLK was simply a damn good anime. TTGL gets my vote.

yeah agree with u, those line " drill "  (will), it's really typical shonen anime type , the bound between Kamina and the strugle of Simon during Kamina death it so epic