Unless you are thenostalgic type, you'll likely settle on an in-line. The can be had for $100 to $800. If you're like most on this forum, you'll end up with several. I suggest starting with something reasonable priced. I just bought a Remington Genesis on sale from Cabelas, paid $120 including shipping and handling and a $35 MFRs rebate. I can recommend the gun as a good one to start out. So are lower end CVAs and Traditions. The Genesis is actually built by Traditions.

If price were no object, I'd get a Savage smokeless gun, or since Blackhorn 209 powder has come out (very little fouling, non-corrosive) maybe a T/C Triumph.