It sure is a rabbit hole. Seems to me first you decide, what are you going to do with it - for me, target/plinking. Then, what's best for that (probably .177 or .22). Then, do you want to cock it every time or no. Which might be dictated by what you can afford. Also will you need to do any upgrades and how much does that cost (like trigger mech/guard). Bigger calibers cost a lot more for ammo. Looks like for my purposes you can get out for probably around 300 and have something that shoots real well. Cocking might get old quick, then, you need to think more like 600 plus whatever you are pumping it with. CO2 is ok, I've had them, but probably not my first choice. Cosmetics can come into it - I like a wood stock, and that will limit you if you insist on it. Obviously for other people with different purposes there are different solutions... yeah, a rabbit hole, but I think some sense can come out of it. I suppose looking for used is an option depending what shape it's in. Oh, yeah, and the noise, that's a factor, depending on the situation. Almost need a chart. My gut says Gamo or Marauder, latter preferred if you can afford it. Funny, these guns cost as much or more than 'real' ones, eh?