In case anyone was interested:
I was curious if, mathematically, starting chain vest + cloth armor would be better when facing a physical bot, so I went about calculating the effective health. Assuming all things equal (And armor mastery/hp+3% mastery), at level 4 Udyr has 37 armor and 848 HP.
Doran's Shield of +247 HP and +20 AR = 1,719 eHP
Chain Vest and Cloth Armor of +63 AR = 1696 eHP
On top of that, Doran's Shield gives an extra 13 HP/5 (taking into consideration the healing CS nerf), so that's 156 extra HP every minute. The starting difference isn't much, but as the match goes on the HP/5 certainly brings shield to the forefront.
And Ninja Tabi is also inferior; Assuming all hits are AA, it's the equivalent of 43 armor at level 4 (Making it a more expensive and less effective chain vest for +20 move speed).