I'm surprise nobody has replied here. I'm interested in hearing other thoughts because I expect this one will have a different answer with every post. A lot will depend on location.
Personally, we use Pfizer's Cattlemaster 4+VL5 for the cowherd and replacement heifers starting at yearling. Its sure not the cheapest, but I wouldn't even consider switching.
For calves, we only vaccinate/process at weaning, so we use a live product. Agri-Labs' Titanium 5 with the Pasteurellas and then booster with a straight Titanium 5. We like to get calves eating and stimulate a good, quick immune response before any blood-letting. The Titanium does a good job for us. Response is faster than a killed product and without the really bad sweats we used to get from some of the other live products.
Alpha-7 from Boehringer on the Clostridial. Always reliable for injection site swelling/knots, but has always been effective for us with just one shot.
Although we don't do it, your loyalty to one company idea is probably good for product support reasons. Our main supplier is Walco/Hi-Pro, so we usually just depend on them for product support. Valley Vet appears to be equally as good. Have to admit, though that Pfizer has excellent customer service.