Any 6" revolver in .357 Magnum if you can find it, like an old Ruger. That will get you excited everytime you go out.
Rather than getting all bummed out about the short sight radius semi-auto and "What am I doing wrong?" kind of feeling, it'll make you a great shooter in short order.
If you can only have one, the .357 is it. Don't waste your money on .38 specials unless it is +P. Boring...