I would like a good smoke and carbon monoxide detector. My problem is that I want to replace the smoke detector that I have which are hard wired or rather plug in. I have no problem finding the battery powered versions but can't find any to plug in. Any suggestions? Also is the plug in version better or the battery?

Buy which ever brand you have in your area. One is as good as the other, Fyrenetics, BRK, Firex, and others.

Of course, some have have recall issues, so check at CPSC Home Page for any recalls.

Since your existing detectors are hard wired, they must remain, as they are required by code. Each detector comes with a short 3 wire whip with plug that plugs into the detector, and splices onto the building wire in the junction box.

Any detector should also have a battery backup, as required by Fire Code, also. Battery only units are for those older buildings that have not been rewired for interconnecting and line voltage detectors.