It is amazing how this market exploded. There are two types of leather care products, conditioners and sealers (as I think of them). Conditioners soak in and loosen up the leather fibers and sealers mostly stay on the surface and keep the glove from drying out and keep sweat out.
In the old days, Neat's Foot Oil and Mink Oil were standard conditioners and Vaseline was the standard sealer. By 10 years ago, Neat's Foot and Mink oils were out (they are not good for leather in the long run supposedly) and we had Lexol (brown bottle) and some beeswax sealers like Obenauf's. The last bottle of Lexol I bought smelled weird (maybe the formula changed, or I just got a weird bottle). Mitt Juice is similar, but expensive. I bought some Voodoo conditioner; it is a lot like Glove Stuff, and I like them both (both a little thicker than Lexol). As for a sealer, Obenauf's is still great. Some new boutique products like Ballplayer's Balm are probably great, but at $12 for 2 oz., it's a bit spendy. Obenauf's is $13 for 4 oz and Lexol is $20 for 17 oz.
Most important thing is not to over condition. Playing catch will break down the leather fibers mechanically. Adding oil will soften them by making them slippery (and it takes a long time for the oil to dry up). If you get it as soft as you want it with a conditioner, then once you use it, it will go too far. But water will cause the leather fibers to delink temporarily. As they dry, they relink up. So getting the glove a little wet before playing catch early on will help the glove break in to your hand, without making it permanently soft (although it seem to speed the break in process a bit).
The sealers don't do much softening, they stay on the surface. Use it in the lining to slow down how much sweat gets in. Sweat has salt, salt retains water, bacteria loves to eat leather, but needs moisture so sweat >>> moisture >>> bacteria >>> dry rot. It is amazing how much faster linings deteriorate in Florida compared to Minnesota.
