It's pretty much been said but I'll reiterate a little bit based on what I have noticed in the store.

LG - Very responsive and very smooth running devices. Never really notice any lag or delays while going through the menus which make them great for texting and also for people who can navigate through the phone menus quickly. On some of the phones though they feel very very plastic-y and cheap. (8360, 5000 series)

Motorola - Slower processors = menu lag. The speaker quality in motos seems to be better and in most cases signal strength is a little better as well. They need to work out the lag issue though, as it cripples the Krave when compared to the Dare. At the risk of getting some flak I'll say that usually I recommend motos to older customers that aren't as text saavy and won't notice the inadequate menu speed.

Samsung - Varies pretty much by device. Hit or miss is probably the most accurate way to sum up samsung as a whole. Battery life on most devices is a little less than their competition but they do make some solid phones. The Alias 2, Omnia, and Flipshot are all pretty solid phones. The u430 is also a very solid entry level device.

Pretty much it all depends on what you need personally in a device, then we can guide you from there.