I don’t know about which of those feeds is best, but I actually fed soaked alfalfa/timothy cubes as the sole forage for three large horses (two seniors and one 7-10-year-old) for a couple of years when the oldies weren’t able to handle baled hay any longer. It was expensive as heck, as you can imagine, but it got them through winters without any issues. They kept their weight, stayed healthy, etc.
I still have the younger horse. He’s 15 now and can obviously eat hay, so he does. But I still like his “feed” to basically be bagged forage with vits/mins, etc. Right now that’s soaked beet pulp shreds, his ration balancer and other supplements, and chopped alfalfa mixed into the mash. It’s fibrous, takes him a little time to eat, and he loves it.
I would add hay cubes in a heartbeat if a hay shortage was making it hard for me to get baled hay. I agree that the Standlee bales can be hit or miss and for that premium price, that’s just unacceptable. I’ve actually been a little upset by the bag of chopped alfalfa I have. Not because the hay quality is bad, it isn’t (and the horse thinks it’s heavenly), but I have found long, thin pieces of baling twine (like one strand of the twine that has unraveled) in the hay. I have to be careful to really sift through it with my hands to make sure there are no tiny threads of baling twine. That’s absurd. Standlee is mighty proud of their products, but they seriously need to work on their quality control.
Still, I do like Standlee’s cubes and pellets and beet pulp, so those are my go-to if I need to up the forage but the baled hay supply is short for whatever reason.