I used to consider OI and volume leading for liquidity, these days I also look at the bid/ask and strongly prefer it to be less than 10% off either bid or ask depending on which side I'm on. However, all things being equal I strongly prefer there to be some OI too. A tight bid/ask could be just one market maker, and what if he decides not to market make as market conditions change? Then I can't exit a position easily. A larger OI/Volume indicate to me that there are (probably) at least be some other participants I could trade with.
But that's just my perception, maybe others could chime in?