Just get yourself a decent quality AGM battery, and there is absolutely no reason to go with dual batteries. And most winching needs are completed in 30-45 seconds so rarely do they drain the battery enough to worry about, especially when the engine is kept running. I've even winched myself off the trail at least twice without the engine running and with just one AGM battery. Nope, doing that did not drain the battery... the engine started right up after fixing the engine issue.
And when doing repetitive pulls, which are rare, just use a little common sense battery management. Just give the alternator a chance to recharge the battery some between pulls and keep the rpms up so the alternator can put more power out.
AGM batteries work better for offroading since they are constructed more ruggedly to resist the shock and vibration of offroading, and they are usually able to provide more current and charge more quickly due to their low internal electrical resistance. If you have the $$$ it's hard to beat Odyssey, Northstar, or Bosch Platinum AGM batteries. If not, most store brand AGM batteries hold up fine.
Do avoid Optima batteries, their quality and lifespan went to hell after they were purchased by Johnson Controls who immediately moved their entire manufacturing line to Mexico. That's when they started using cheaper materials and also stopped using pure lead.