Items and gear play a large part of Dauntless. That's not entirely surprising considering it's a loot-em-up in the vein of Monster Hunter, but it's hard for new players to understand what is, or isn't good armor. At a basic level, you should always use a mix-and-match set to ensure that you get a varied amount of perks. Not only that, but all armor in Dauntless has the same defensive rating, so what seperates them is often their elemental damage, and cell slots (paramount to end-game). Here's the top 5, with full details by DarkHero below:

5. Drask 

4. Rift Stalker

3. Koshai

2. Hellion

1. Rezakiri