look up leupold tracking issues and you will find quite a bit of information.
Printable View
Delta 4-24x50.
That’s fair with vortex they have two scopes that I would trust, but they have a heap of rubbish also, Nightforce on the other hand have a smaller market less volume but I am sure per sample would leave the leupold for dead. But you are right there is bad information on any product.
optical clarity & low light performance has to be number one - a fuzzy magnified image is not going to help.
Apart from those listed above you might want to consider Swaro Z5 3.5-18 x44, would fit into your budget. Or if you want "more mag" then Zeiss Z6 5-30x50. New price its not going to fit your budget but they come up 2nd hand at about $2k from time to time.
Sightron, had an stac 3-16 and it was epic. An S111 is much better glass but same dials. Shot magpies to 430 and plovers to 540 so 15x zoom is enough. Regret selling that scope