The Athlon Ares 15-45x is far superior to the Vortex Razor for around $550 maybe even cheaper from your price friendliest dealer over the phone. I think nothing comes even close to it short of paying at least twice to triple the price like a Kowa. Athlon with their current Chinese glass simply cannot be beat rivaling some really good Japanese optics believe it or not. Their sub $300 Chinese Midas G2 binoculars already is an upgrade compared to your Viper binoculars and their $400 Cronus UHD binoculars even better upgrade. Their new Chinese 20-60x Cronus G2 spotter is better than their previous G1 made in Japan and worth the $850 and way better than the G1 Vortex Razor RZR 01 spotter selling for $800-$1000 also Chinese just like the current more expensive Burris Signature HD spotter same spotter as the G1 Razor.
If you want a bang for your buck in an unknown optic with excellent way above average glass almost like the Athlon Cronus G2, lifetime warranty Chinese, the Hawke Endurance 25-75x85 best in class when they go on sale for under $500 image quality is almost sheer perfection even on high magnification. Don't pay regular price for it, it's still Chinese and overall quality of construction is not as good as Athlon not even close and $500 is the most I'd recommend buying it for phenomenal glass inside less than perfect build quality but at least it has a lifetime warranty. The baby version of this spotter is on a fantastic deal at Optics Planet however it's earned credit towards next purchase instead of instant discount so it's like $200-$250 for it considering the store credit you get after buying it and don't forget to sign up for the 10% discount code.