We chose the Angel Care monitor before our baby was born and received it as a shower gift. The main feature that convinced us was the motion pad that lays under the baby mattress. This monitor comes with an alarm feature so that if the infant stops breathing, you'll be awoken. For a nervous new parent, this was key to my sanity! Now that my daughter is old enough to scoot around the crib, we have removed the pad and just use it as a regular monitor.
The range of this thing is great. We have 2 parent units and have taken them outside with us while the baby was napping and were still able to hear her. It can operate on batteries or plug, and we use both. This thing does tend to eat up the batteries so we have to make sure to plug it back in when we're done. But the units are very portable and have a good amount of sound adjustment available. Great product for new parents.