40K Question: Medusa Or Colossus Or Griffon?

I'm thinking about some arty for the Valhallans. The default is to just build a Medusa gun for my already-completed Basilisk. The bassie has too great a minimum range to amount to much in games that I may play.

Marines in cover? Colossus deads 'em like d-CON but the minimum range is a drag for the average game as well... and the model is all-around expensive too. Great for apocalypse though.

Medusa has some versatility with two differet rounds available, fires direct and has good range for the average table (and no minimum range.)

But looking at stats, I think I like the Griffon the most, at 70 something points and re-rolling scatter, it kills most things in open ground and seems a great value for what it does. I can easily build a heavy mortar to sit in my salamander and park that puppy in a back corner.

Thoughts?