How is the sealing surfaces on the axles?
Yep. There is a reason the seals are failing. They don't "blow." They wear out for some good reason. If you can find the reason, fix it. Or use grease. Either will work well. We've all run car & truck front wheel bearings with grease for years. I've run industrial bearings with grease for years. I had some spherical roller bearings on a 200 hp 1750 rpm fan shaft that ran cooler with grease than with oil.
There is no magically good grease. All the greases mentioned will work very well, and more besides. Schaeffer is the pick of the litter. The main thing is to not over fill the bearings. Over filled cause the grease to churn, get overheated, the grease fails, then the bearings fail. The old story about more bearings failing from too much grease than from too little remains true.