I have a scope with a 56mm bell and my shooting tightened up quite a bit once I dropped to a 40 mm scope on that rifle.
Don't get gagged by the buy the best stuff. This is all ford vs chevy territory. Some are selling scopes, some just really like what they have.
All brands have a signature version - Vortex Viper is the signature Vortex scope - it is the one that helped them achieve success. I have no idea about the diamondback versions but plenty of folks really like them. I'd probably prefer a Razor version (step up from Viper).
Thanks to our market society, most items of a similar cost will have a similar value. Some focus better, some dial better, some are better in low light, some do all the above. What I'm saying is that a $500 scope should function the same or similar to another $500 scope. The higher you go in value, the less difference between optics - it will be harder to denote why a $2,000 scope is better than a $1,500 scope. And it might not be worth it to you.
If you go and look thru a bunch of scopes in your price range, you will find one that fits your eye better, that you like better. BUT you have a decent discount so your $$$$ is getting a Vortex with a higher price tag/value compared to the other scopes.
If I was going below $250 it would be a Vortex Diamondback, below $500 it would be a Leupold VX-3i, below $1,000 it would be a Meopta. If I wanted the very best it might be a Swarovski.
Based on your question - you just want a scope for your gun and don't plan on doing anything fancy with it. Vortex is a good brand name.