Use case for each artillery caliber? Towed vs SPG?

Hey everyone I just bought Warno and wanted to put more of an artillery focus playing because artillery is cool. I used to play WG:RD but only ever utilized mortars to support a maneuver-warfare playstyle via suppression/smoke.

On the mortars side, I mainly see 81mm, 107mm, and 120mm mortars being the most prominent for bluefor, and 82mm and 120mm being prominent redfor.

Howitzers, I mostly see 122mm and 152mm artillery along with an odd 76mm and 130mm. Bluefor appears to primarily be 105mm and 155mm.

Then there's also the much larger 175mm and 203mm monstrosities of guns. I'm guessing these ones are for sniping something out accurately with a big boom?

Pros/cons best/worst use cases of each shell caliber? Which kind of artillery is generally preferred (or hated) amongst the player base?

And any use case for using towed artillery in place of an SPG, aside from cost?

Not trying to be "support player", just someone who wants to change things up a bit to have a bit more of an attritional playstyle for the lols. I'd probably be playing everything from 1v1 to 10v10 so all perspectives are welcomed.