Marlin or Ruger for a semi-auto, CZ for a bolt. I've got both a Marlin and CZ, but only shoot the CZ. The factory sights are awesome, the gun is comfortable, and it's deadly accurate. I had to take the scope off of it. I got tired of hitting everything I aimed at. True story.
Anyway, the Ruger is a great starter gun. It's quick handling, and fairly accurate, making it very fun. The only reason I don't own one is because I have an insatiable urge to tinker. Refer to AKElroy's post. That would be me. lol If you go with the Ruger, I'm sure you won't be disappointed. Just remember that rimfires, especially semi-autos, are picky about the ammo they will cycle and shoot reliably AND accurately. Be sure to try several different brands.