Boot brand doesn't matter, really. There are so many styles now, too. You can get one that fits your needs according to budget and ease of application for the amount of time you will use them.
And I'm not sure what your budget is or if you board your horse, so this may not be feasable, but you can put round gravel (it can be small river rock or pea gravel, or larger stones, just so long as they are smooth) in a high traffic area, say around the water trough, in the walk way of a gate he goes through frequently. The stones, if they aren't sharp, won't bruise him, will help toughen the feet and exfoliate the sole, and will help get rid of those muddy spots. The key is to put them a few inches deep, so they aren't hard on him, but have some give. They'll pack down and scatter over time, and if your horse has toughened by then, you may not need to top them off very often to keep them deep, unless you want to.
Personally, I have landscaping gravel along the front of the stalls of the barn, and in front of the watering hole. Cuts down on erosion, and their feet look pretty good. I have sandy, arena-like soil that wouldn't toughen any hoof at all, so I've compromised by buying rocks. I started with river gravel, several bags, mind you, from Lowes but you can probably save by having a truck load from the local gravel company put in. We later put some lava rock on top, and it's really polished up those soles!
Older horses may never be as tough if they've been shod most of their life. Depending on how the shoes were applied, and you're horses' natural sole thickness, etc. But after years of shoeing the corium can be damaged enough it just doesn't grow quite as well, period. That's when you get boots for riding and every wins. We have a 25yr old that was shod all his life, until a few years ago, and he's a tad thinner soled. I can ride on concrete with him, or hard ground, but road gravel he's very careful about, so I boot him. I use Cavallos on him-he's round footed, and he's old so we don't ride him much, so they never rub on him, but if we rode more, would use Easyboot Epics, Gloves, or Bares.
Pine Tar is a good antiseptic type for horses, so in the sole it wouldn't toughen it, really, but it would help fend off thrush.