AmerginLiath
Adventurer
Both of these have tradeoffs, of course. If the wizard readies, the spell could be disrupted, the orc gets a round of attacks in before the paralysis hits, and the wizard gives up the ability to cast shield for a round. If the fighter and rogue ready, they sacrifice their ability to make OAs for a round. (Overall, I would say it's almost always better to have the fighter and rogue be the ones to ready attacks. However, it can be hard to coordinate that kind of thing.)
One of the things that I'm loving about the 5e ruleset, the more that I look into it, is the tradeoffs. Opportunity cost is BIG in this edition. We see here the idea of risk vs. reward that's hard to fully optimize as one correct answer – either could go right or wrong depending on a number of variables and the default order might prove the least tricky option (less chance of reward, but without the risk of spending the opportunity cost of reactions for nothing if saves are made). The beauty of of bounded accuracy is this specific "swinginess" that makes it all a tactical gamble based as heavily on specific circumstances (the Inspiration rules on Advantage) as anything else...