As it currently stands, there is one type of shield added per content, and that is the option Paladin is stuck with, essentially leaving us with a useless variable. What I am proposing is creating additional shields per content that have the same primary and secondary stats, but have different block rates and strengths.

As an example I will use Leviathan's Tidal Wave, as this is the only level I have stats for all three shield types for:

Tidal Wave Shield (existing shield, buckler type) - bstr 106 brate 307 STR 11 VIT 12 crit 8 det 8
Tidal Wave Kite - bstr 193 brate 193 STR 11 VIT 12 crit 8 det 8
Tidal Wave Tower - bstr304 brate 119 STR 11 VIT 12 crit 8 det 8

All three shields have the same VIT/STR/CRIT/DET, but the different block strength and block rates would provide us with options, making these block stats feel useful.

Since level 50, the following are the item levels where there have been more than one option for shield types.
level 50 content
---iLv90 buckler/kite
---iLv100 buckler/kite/tower (only option for all three)
---iLv110 kite/tower

skipping the 51-59 range as there is only one shield per ilvl/lvl

level 60 content
---i180 kite/tower (tower is bismarck crafted)
---i210 kite/tower