Go for the one you want redeemables from.

There is no need for head-breaking calculations with your query, just simple explanations would do the job .. Just like what Zathroth said, go for the one you want redeemables from .. To further explain this, if you want to gain power then both events are good but if you want to have a chance also for hitting the Jackpot Event Ninja for this week then you may consider playing the Lucky Stars Wheel, while obtaining Stars for you to use to redeem items you want such as the Myoboku Gifts or the Charm Packs, then choose Lucky Star, as well as the Ninja Fragments available to redeem there if you want to have them .. On the other event, Lucky Board, Throwing dices are best made by 10s since doing it by 10s, can give you a chance to get 1 free dice .. While throwing dices you will get some items for power and some are scrolls or the summon fragments,and you will also get points for you to use to redeem some power items like the Refine Optional Boxes and the Charms Packs, or go for the Clothing Summer Suit or the Ninja Fragments like Shisui ..

so once again, choose the one with the redeemables you want to get ..