Hi Susan,
ProZinc would be familiar to you in its action, although it's generally slower in onset, doesn't drop them as low and has longer duration than Vetsulin. It's an "in and out" insulin so once a dose is done, it's done. You have flexibility in dose timing and how often you make dose changes similar to Vetsulin. Plus or minus an hour in dose scheduling isn't a problem when life gets in the way. However, it's much more expensive than Vetsulin ($100-$120 per 10 mL vial) and you'll go through it just as quickly.
Lantus is another universe as insulins go. It's a depot insulin so part of every shot is stored in a sort of slow release form so there's insulin acting all the time. The effects of a dose can take a few days to show because of this depot. There's very little flexibility in dose timing (12/12 is required and deviations have to be planned in no more than 30 minute increments over days) and doses have to be held as long as a week or more. There are two clear protocols to follow. You can read about them in the yellow stickies on that forum. It's a very gentle, slow acting, long duration insulin and many cats do very well on it. It's extremely expensive in the US ($400+ per 10 mL vial) so many order from a Canadian pharmacy, Marks Marine Pharmacy in Vancouver. It's a more concentrated U100 insulin so the cost ends up being similar to ProZinc or cheaper if you order from Canada.
Bouncy cats will bounce on either ProZinc or Lantus as I can attest.

The bouncers can improve a little or a lot on Lantus. Teasel is in the "a little" category. I can say, though, that he feels better on Lantus than he did on ProZinc.
@Lisa and Smoky had very good results switching Smoky from Vetsulin to ProZinc.
Does this help? Ask anything else you want to know.