It's a tough situation.
Wooton - Good pedigree but in a relegated team last season and wasn't rated at all by their fans, so far for us I think he's looked weak, slow & his positional sense poor.
Edwards - Unpopular thing to say, but I think he's definitely overrated, he's good at winning aerial battles but his positional sense is (like Wooton's) poor and his distribution is Guy Branston-esc.
Canavan - Thought he put in good performances against Coventry & Wycombe, I also hear he played well against Bristol. I'm not saying he's been anything special, but better than the two above.
Grant - We know nothing about him, but considering how poorly we've been defending, he can't be doing brilliantly in training considering he can't even get a place in the squad.