I have three regular Vanquishers and one command tank Vanquisher and I've played a few test games with them and they did quite well against my space marines (to be fair I am aware that my space marines need more anti tank firepower but that is beside the point). I had three Vanquishers take down a Land Raider and a Redemptor Dreadnought almost singlehandedly in one turn, they didn't even get to fire their sponsors as they weren't in range. I have a feeling that in general the opinion of the Vanquisher is that it's an alright trading piece because it's cheap but it's not that great overall. I don't get why that is because, even without orders or standing still, I've seen them quite regularly hit and do quite a bit of damage to targets with the Vanquisher Battle Canon. Also if you use a Sentinel's ability (I think it's called daring recon) to give a reroll to hit on 1s, you then also use Take Aim! and you don't move then you are effectively hit on twos and you reroll ones. I don't know, am I just missing something? Is my perception warped because I have only done test games against my own Space Marines which I know have a lack of armour and anti armour (I have a Land Raider, a Redemptor Dread and a Ballistus Dread)? Is there some other reason that the Vanquisher isn't considered to be that good?
Sorry for the rant, I've just been thinking about this for a bit and wanted to ask everyone else here about their opinions.