I would say if the entire feline diabetes community is reflected by the percentages here, then yes, it seems more and more vets are prescribing lantus than any other insulin. It probably has to do with the existence of the studies done and the tight regulation protocol(s) used. There's a lot of scientific data around to back up the claim that Lantus works "best".
There used to be a "PZI" made by Idexx (I think), that was made from pig and cow pancreases. That was discontinued a few years ago. It was replaced by both compounded PZI, made by places like BCP and VPA and several other labs (It is cow-based) and by the creation of Prozinc. In tests against the old PZI that was being discontinued, Prozinc was found to work at least as well, and in some ways better. It's human rDNA insulin, specially engineered to be used on cats.
I am not aware of any studies that have been conducted that compare Lantus directly to Prozinc. There was at least one study that compared Lantus to Idexx PZI and Humulin. Lantus won that test significantly. All the Lantus cats went into remission, while only 3 of the PZI cats did. (each insulin was given to 8 cats). None of the Humulin kitties went off the juice.
The only study that I have seen using Prozinc was against the old Idexx PZI. It was found to have a longer duration (10-14 hours) and a later nadir. So it was determined to be a suitable substitute for the old PZI.
Last year, there was a big shortage of Prozinc, and it was very hard to find. But that shortage went away and now it is supposed to be readily available. Conversely, compounded PZI is supposed be to getting harder to find, and finding a reliable source of supply is more difficult.
Carl