Tikka Lover is right, that you have asked an opinion question and you know what they say about opinions. But because I have Leupold scopes on my rifles and am about to recommend Sightron to you, hope my particular opinion has some weight.
All three of my rifles wear Leupold scopes.
My 260 by MCR
My 300RUM by MCR
4-14x40 VX3...(you have to read to the end to see the upgrade from VXII to the VX3)
My 280 - Updated!
The 260 is my 'main' rifle as it sees the most action. I use it for targets, varmints, deer, f-class and tactical competition. Because it is used in tactical competition, Leupold's TMR reticle cannot be beat. It is graduated in .5mils and at the endges it is graduated in .2mils. This allows you to precisely mil targets. What's more, the crosshairs of the reticle don't actually cross. There's a small gap. This is great because if you are shooting at a small target, like a groundhog, at longrange, your reticle will not cover-up the target.
I then put the same reticle in the other scopes so that when i transition from one rifle to the next, my scope picture remains the same.
So, if you have some interest in tactical competition where you might have to engage some UKD (unknown distance) targets and you have to mil them, Leupold with the TMR reticle is the way to go.
Many times I have been on a range or at a competition and heard guys bash Leupold for various reasons. My experience is that they are clear glass, great reticle choices and reliable/repeatable turrets.
If you are not interested in tactical competition though, it's tough to beat the Sightron SIII scopes. Their glass is clear (as good, if not better than Leupold), turret adjustments are reliable/repeatable and they have some great choices in reticles including mil-dot and MOA, although they put a small target dot in the center of their MOA reticles. I'm not a fan of the small dot as it can cover up small targets at longrange.
The best testimonial I have for the Sightron SIII scopes is that four out of five of my friends that are longrange hunters use SIII scopes. My one buddy that does not use SIII has US Optics on his rifles.
An additional point that makes the SIIIs attractive is their price. You get a great scope for ~$800. that is easily hundreds less than comparable competition from Leupold and Nightforce.
Sum it all up....
Shoot tactical competition = Leupold
Not shooting tactical competition = Sightron SIII