Of the 3 you mentioned, I'd suggest the Samsung A920. I've had one since June 2006 when I transferred from the iDEN side of the house to the CDMA one and I absolutely love mine. Part of the reason I do is the fact I'm into music and like to listen to my MP3 during down time at the store.
The dual stereo speakers are pretty decent for a handset, the Bluetooth is convenient and the standard battery of the A920 blows the other 2 Samsungs out of the water as far as digital standby and talk time are concerned.
Personally, I'm not a big fan of Motorola. Had to carry the i730 when I worked in a legacy Nextel(iDEN) retail store. To me Motorola just doesn't have the sparkle and shine like the other handset manufacturers whne it comes...
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i would suggest you wait for the razr so that you can have options - for me i'll go with moto - ive learned that there are some known issues on samsung phones especially with softwares picmail etc. but it still up to you - just look for the phone that would fit your needs - you know how complex phone works and if it is not well taken care of it may not last