Thank you for the shoutout
@carbonbased
Just about all scopes mentioned here are good options. Reticles are an individual thing. For someone fairly new to this, I would probably not start with Horus. Aside from my personal dislike for them, when you are new, less is more.
For gas guns, unless it is something really substantial, I tend to stick with scopes that are a little bit on compact side of things. For most long range applications, I think the need for a lot of magnification is a bit overstated. That having been said, if you have a 15 pound gas gun (I have one of those and it has a 5-25x56 TT on it most of the time), it does not matter. If it is something a little more handholdable, I would go with a more compact design.
In the grand scheme of things, something that tops out around 20x or so is a good option and of those the ZCO 4-20x50 is the best one currently available, I think.
S&B has three good options: 3-20x50, 3-20x50US and 5-20x50US, although it tunneling does not bother you much, the original 4-16x44 and 4-16x50 are really nice. The 4-16x44 was one of my favourite scopes ever made.
Nightforce has the excellent 4-16x42 and 4-16x50
March has 3-24x52 and 3-24x42 (I have the 52mm version). There is also a 4.5-28x52, but it is not out yet
Leupold has the Mark 5 3.6-18x44
Steiner's upcoming M7Xi 2.9-20x50 looks promising, but I doubt we will see it in the US before SHOT.
TT has the 3-15x50
Given the mil discount and sub-$3k (I think) budget limitations, both Leupold and Nighforce have a lot to offer. Personally, for a gas gun, it is hard to do better than Mark 5 3.6-18x44 with illuminated TMR if you want a simpler reticle or ATACR F1 4-16x42 with Mil-XT if you want a tree reticle.
ILya