The question would be what sort of a car you want to have?
Drivable car should have no les than 8.7:1 but if you want mad boost with big turbo, go as low as you can... the lower the CR the higher the boosts safe limit. You'll have the lag, but you'll have power that you will not handle when the turbo kickes in By the way with to low CR it is hard to start the engine. Thats' my opinion... 8.2:1 for me always as I like the power kick whick you don't feel so much with high CR cars and low boost. That's what they do to NA hondas ... high CR, low boost... 250 BHP and it pools all the time, but not as fun as our fords with that boost kick