As each manufacturer appears to have their own proprietary battery It's rather difficult to buy wisely.
FWIW don't buy Makita 18V stuff if the batteries are going to spend months on the shelf unused. The tools are excellent, but the BMS has an evil failure mode whereby deep-discharged batteries' electronics brick themselves "for safety reasons" on the third consecutive failed attempt at charging.
(PSA: If you have a Makita battery that fails to charge, proceed directly to your nearest electronics geek with a bench power supply, rather than shoving it back in the charger repeatedly. Bringing the cell that powers the BMS back up to normal voltage range allows it to charge normally, but only if you do that before it bricks itself.)
I am not going to need more cordless tools
I think that's the mistake everyone makes...
so I'm wondering more about battery life management at this time.
FWIW, from experience of building scenery, which is the closest I'm ever likely to come to laying a floor, n+1 smaller batteries beat n big ones (where n is the number of tools in use at once). That way you're not having to hang around waiting for them to charge.
And as robgul says, if you're going to be cheap about it and don't need the portability, stick to corded. Certainly don't touch anything that's using NiCad batteries with a barge pole.