What to buy?

[Rowan]

I'd go for Sharpthorn (3 mil+ ) and Bronze Bolts (800k or so).

If you own those go for Aegis.

I value the shooting aspect of Pavise higher than shielding which to me is more a backup/versatility option.

This is good advice, I have a pavise, got a nice crossbow and set of bolts but haven't bothered with shield. Generally there will be a Infantry in your game that can fill the shielding position and using crossbow is more effective. I beleve that pavise class should just be a backup of royal guard.