Due to the few types of boots out there and the rarity of creatures dropping them, they can be very expensive. Leather Boots can be found in great abundance, but anything (including Crocodile Boots) except sandals will cost a lot more.
Arguably, the strongest boots are the Depth Calcei, though there now exist elemental variations for all vocations. The Magma Boots, for example, are the most defensive a mage can wear when fighting fire-oriented creatures, while the very rare Dragon Scale Boots would be the best choice for knights.
Many people use Boots of Haste to increase their walking pace. A favorite method amongst knights is to carry Steel Boots around with them to slip on instead of Boots of Haste when they fight fierce monsters. Higher level knights and paladins may opt to replace steel boots with Draken Boots, which provides equivalent defense and +15 speed.
The best boots depend on the scenarios they are used in and the vocation of the player. For example, a knight casually hunting primarily physical-damaging creatures will be the Guardian/Soft Boots duo, whereas a paladin may wish to keep a distance from their opponent and opt for Boots of Haste or Draken Boots.