Depends on what is your goal.

So lets try to evaluate them depending on it.

1) Are you in a new server or your power is under 60k bp?

Then the best event by far regardless what your goal is is lucky board.

2) Are you in your late game (90k+ bp) and you want to piece an op ninja?

Then the best event to go is konoha great tree if you plan to invest 25k+ coupons and your goal is to get two of the redeemable options at the same time.

If, instead,you want a single ninja then the best event is lucky * 500 rolls redemption part (except this week) and after it, not by much, great plates 3500 rolls redemption part.

3) Are you in your late game (90k+ bp) and you want to increasedramatically your power?

Then the best event by far is... konoha outlet in combination with fukurukumaru deal (yes,this week one... )

If you plan to invest 25-30k coupons that's the best event by far (the pack with 450 myoboku gifts, the pack with 4k unbound runes, the 10% discounted tactics pages are the best investments you can do currently and with the 50-60 scratch cards you can get some very good rewards as free redeemable items, overall is the only way to redeem ability scrolls currently).