Here's my thoughts...
1. Mario is the sure bet. proven, young, and will have an impact.
2. Colston is next. We are desperate for a WR. Colston catches just about everything thrown to him. He's not that old, and can help groom some younger guys. Injury and age are a concern.
3. Jackson is 3rd. His production isn't consistent. However, I think besides Mario, he has the biggest potential upside. Given the bidding war for him, he slides below Colston. He also has injury and age concerns as Colston.
4. Nicks is last. I love me some Nicks, but he's going to generate a huge salary for a position we aren't in dire need for. I'd love him in addition...but he's going to demand too much loot. If he were a LT, I'd have him right up w/ Mario.
I simply think Mario is the bird in hand. virtually no downside at all...