Totally recommend NAF Hoof & Sole or Hoof Moist both of which I have used in the past with great success even the blacksmith has commented on the good conditioner when other horses he shod were dry and brittle, and still using Naf Hoof Moist now as are a lot of my liveries with good results.
I use Effol hoof oil which really prevents my tbs feet from becoming cracked and dry. put on day and night and creates protective barrier to stop them getting wet/dry/wet/dry in the field. Has worked wonders so would highly recommend it but don't know if its what your looking for as doesn't necassarily create moisture, more preventative.
effol or hoof moist but not the black coloured ones of either. i was also told that if you wet the horses hooves first then apply whichever over the top it helps to lock some of the water in.
i find the original cornucrescine works really well, and if you apply it by hand or rub it into your own finger nails it makes them grow like stink. talons in two weeks.