Can’t go wrong with the 1377.

Full disclosure... it says 10 pumps max, but mine tops out on power at about 14 pumps. I filed the rear sight to a V, and painted the front sight.

Available mods are nearly unlimited. So even if you decide you want something better, you can upgrade the 1377 to your hearts desire.
Everything is available. Standard and high end barrels in a wide variety of lengths, exotic wood stocks, rifle type buttstocks, adjustable triggers, high flow valves, the works.