For the Anniversary event I spent ~50K of my saved HH kobans (most of my stash).
30x (16.2K kobans) Epic Pachinko x1 (tried my luck, so see if I could beat the odds and did not)
Received some good legendary gear, Sailor Celsius and Kyoto
2x (10.8K) Epic Pachinko x10
Received some meh gear, Gossy and Cop Nika
The remaining 23K was spent on fight refills. No 10x spins -- it felt like these would've just cost me chances as I'd have fewer kobans for the refills.
Received:
Windia, Music Sylvia, Treasure, Bunny's Mother, Deitra, Lady Meta, Union Elizabeth, Noella, Neanderthal Gork, Victoria, Juin Lelierre
So 50K spent to get 15 girls, or about 3300 kobans/girl. Better than straight-up 10x spins, so I'm super happy!
If I hadn't gambled a little with single spins, it would've been 16.