It really does depend on what you want to counter. Van Vets are quite cheap for the punch they pack but are better against some foes than others.
If you are having problems with big monsters rampaging through your lines then what you want is something that can tie them up until a heavy hitter like Captain Smash can hop over to deal with them. Van Vets with Storm shields are great for this as for under 100 points, you can have a unit with a 3++ save throughout. That will frustrate anything short of a Blood Thirster for a turn or two.
On the other hand, an Ork horde would swallow such a unit without stopping to chew. If you are trying to stop big units swamping your lines, Death Company are probably the cheapest source of mass attacks. Add Lemartes for cheap rerolls and he is a decent beatstick in his own right.
Sanguinary Guard are too expensive for counter-assault IMHO. By the time you have spent the points on tooling them up, you have a unit that you cannot afford to leave sitting on the sidelines. They need to be charging enemy units of choice to start earning their points back.
Edited by Karhedronuk, 25 March 2019 - 09:05 AM.
Sanguinius stood up, stretching his wings to their full extent. He flexed his hands. "I need no blade".
It was as though Sanguinius gleamed with pale light, his face white, eyes becoming blood-red, surrounded by the golden crown of flowing hair. Guilliman had witnessed glimpses of of his brother's wrath before, but had never seen the true Blood Angel unleashed. Sanguinius surged forward on alabaster wings, half a meter from the floor, whiteness streaming from him like flames.