If your hunting public, I would think about 1st season to get on unpressured birds and to beat the flurry of mushroom hunters.
On private, in years past I always focused on 2nd season with variable success, but recently with a busy schedule I've been doing 4th with great results. Lot more foliage, but the Toms seem to respond better to calling for me anyways. But for the record, I would choose late 3rd season if I had zero schedule conflicts.