First off,I have 5 Sightron SIII 6-24x50 scopes,that's all the magnification that you would ever need shooting out as far as you want. Shooting long range with really high magnification is usually a big negative because of having a mirage issue. If it's going to be a dedicated target shooting rifle,a fixed power scope would also be a better choice,a 10x or 16x would be plenty of scope for you.
Reticle choice depends on what you prefer,but using a Mil-dot or any of the various modified versions of a Mil-dot reticle really helps with hold off points for adjusting for the wind. If you learn how to use a Mil-dot type reticle,you will never use another for shooting/hunting at farther ranges.For target shooting,I like the MOA-2 reticle that I have on 2 of my scopes,the lines are thinner than the standard Mil-dot reticle on my others.
Unless you want a First Focal Plane reticle scope,the Sightron SIII is a great scope with excellent glass,tracking,and repeatability. The Vortex Viper PST is also another good choice,but IMO,the glass isn't as good as Sightron's,but they do have a few more bells & whistles and they do offer First Focal Plane reticles.Another to think about would be the Weaver Tactical series.They have great glass,and are First Focal Plane.
Stepping up to the Nightforce NSX line will offer you an even better class of optics for about double the price,but worth every penny.
If you don't know what the difference between First and Second focal plane reticles,here's a simple explanation.
On a First focal plane,the reticle grows in size along with the target image when you increase the magnification,so your always able to use the same distance between the dots/lines on the reticle.
On a Second focal plane,the reticle size stays the same,and the target image gets bigger with magnification.You need to know what the measurement value for the magnification is to correctly use the reticle for ranging the distance/size of a target/animal. It's simple math,but if your shooting at know distances it is easy to calculate.
Depending on the type of reticle,a First focal plane can interfere with you being able to see the target because the reticle grows in size with the target,you usually don't have this issue with a Second focal plane because only the target image grows in size.