When I go to buy gear, I first look at who makes it, UG, HG, MG etc... Often there is no option for human grade, i.e, EQ for example.
From their, if there is nothing available as a Human Grade choice, I would look at who makes the dosages I want. I know a few people who would never use UG or Mexi, but end up turning to them, just because they need the higher dosed gear for their cycle otherwise they will be freakin pincushions. These are usually the folks who run higher dosed cycles.
For instance, I would much rather run UG NPP so I can run it at 100mg/ml than 25mg/ml which is the most common human grade dosage. Some go to 50mg/ml, but thats still half what I can do with UG NPP. There is no vet lab that I know of that makes NPP at 100mg/ml, so .. this leaves me with UG for my options. Then I am going with labs that I have researched to have good reps, and who have been tested a few different times, been around a while, and with good feedback. Basically just ones that I trust.
On the other hand ... If i were to run test for example, 250mg of enanthate is a good enough dosage for me. I am going human grade on this one, you can get them fairly cheap as well in the overall grand scheme of things. I guess it really depends on what I am going to run AND at what dose, that determines what i am going to order. But ... i will always opt for human grade first .. then check out my other options from there. I dont mind spending a little extra cash, (and I am not rich by any means) to get what I want. If you look around, you can find everything for a better price!
They all have their place I guess amongst us juicers i guess, whether it be price, or quality, or mg concentration or whatever etc.. I guess we should at least be thankfull we have the options we have! lol