Leupold did fall behind the pack, relying on their reputation to sell the product. They have come around finally with the introduction of new & improved models; the MK 4 M5-A, the MK 6 & finally the Mark 8 line (at a substantially increased price).
BOTW & Greybull Precision used Leupy exclusively for many years with BOTW moving from Leupy to Huskemaw
& finally to NightForce. I believe Greybull still uses the 4.5-14 Leupy.
Leupold has one of the (if not the) greatest Customer Services departments in the industry.
I really don't think you can go wrong with either, some say the Leupy has better glass & less glare IDK. I've owned probably a dozen leupolds & a couple MK4's, I haven't broken one yet.... If only Leupy would offer a dern MOA reticle!
If you want to run MOA, buy the Vortex, if you use Mils, I'd probably run the MK 4 & TMR.