Soy formula ?

LSU628

At our appt today since DS tested negative for a soy allergy, the allergist wants to slowly introduce soy formula and make the transition for Elecare to soy. Is there any difference in the different soy formulas on the market? Is one more highly recommended than the others? In my brief research I found that some articles voiced concerns about the high levels of corn syrup or sugar in some of the brands.

LSU628

Thanks- Earth's Best was one of the brands I was considering. I'm just having difficulty finding it in local stores.  I know I can order it online, but the stress of running out of formula before my next shipment arrives (like with the Elecare) kinda worries me.