Guys, don't underestimate how much of a difference 20% make. To leave a few examples (adding ~130% stamp for a decent late game grid comparison, break even point for Takemikazuchi to surpass Girimehkala):
Ele advantage:
1) with 40/20 char atk eidolon: break point: 100% assault, at 130%: 1.8% damage difference
2) with 40% ele atk eidolon (phoenix, thunderbird): break point: 210% assault, at 130%: -4.5% difference
3) Kirin .. like any Kirin would ever use Take
No ele advantage (why would you ever play thunder vs. neutral element unless you got Kirin):
4) with 40/20 char atk eidolon: break point: 30% assault, at 130%: 9.7% damage difference
5) with 40% ele atk eidolon (phoenix, thunderbird): break point: 135% assault, at 130%: -0.3% difference
6) Kirin: break point once again above 230% assault
In the end, the most common situation for high ranked people with good thunder grids would probably be 1) in which case, Take would be slightly better, followed by 2) in which case Giri would be significantly better. The better active is a bit of a plus for Take, but unless the majority of your friendlist is r90+, Giri is the better choice in my opinion. She might be slightly worse for some, but a lot better for others and if you and your friends are still newer, then she's pretty much always quite a lot better.
But if you consider the break points above, you should be able to form your own opinion on what fits best for you currently.