First off and foremost, I dislike most Motorola phones. They are usually nicely built phones, but the UI has a major lack in usability. The UI added over Android isn't as streamlined and user friendly as others. I know of numerous counts of people have both hardware and software issues, mostly in dealing with Motorola phones. Motorola as well is usually late to the party when it comes to updates as well. LG as well falls in the late to the party. Samsung make great devices, usually right on the ball with updates. Touchwiz UI is highly liked and has a great overall usability. Samsung devices as well are never the ones the jump the gun on hardware as well. They like to sit it out a little while longer to get the feel of the technology, and install parts that work. LG talked themselves up, but dropped the ball. They make decent low-mid level Android devices. Then you have HTC, which I prefer for phone branding. HTC usually make good solid devices, and Sense UI is pretty straight forward UI. Good user interface, seems pretty fluent but does occasionally have hiccups like every other UI. HTC has had a good and bad track record, much like everyone else.
Motorola Razr
Overall fairly decent specs on the phone. TI OMAP4430 1.2Ghz dual, decent but definitely not the most up to date. Decent 8MP camera, supports 1080p, and has front facing camera. Still along the lines of MotoBLUR UI, but Motorola thinks not. Battery life is fair, nothing to superb. People have complained of hurting their hands/wrist because of the thin design, but wide in width. A huge downfall is the battery in this is not user accessible. Meaning.... something happens to the battery... your SOL. No battery pulls if your phone locks up either. Built to be rugged, and the glass on the screen holds up to minor abuse.
Samsung Charge
More or less the Samsung Galaxy but in a 4g form. It is a good low to mid level phone, a little outdated. Only packing a single 1Ghz core, but a Cortex A8 Hummingbird. If you are into tweaking, these things have some potential. Battery life isn't the greatest, actually seems a little lower than other. A few issues is the signal seems on the weaker side. Sounds to me like the "death grip" or you have to hold the phone a certain way. Another bad is it has physical buttons with decent size gaps around them. Likely to load up with lint and such, not including spilling coke on them and making them sticky.
HTC Rezound
I actually had this phone for a week and enjoyed it. It packed with some of the most powerful hardware to date. Overall a great experience with the phone, had nice Beats headphones which is a bonus. Since you said you love music, this phone is directed towards you. Running Sense UI I didn't have any issues with it. Everything was fluent and overall enjoyable. Battery life was decent, would expect it to last a day, also extended batteries available. Some of the downsides to the phone is users have had issues with interference and static when listening to audio through the headphones. This has been determined to be the phone at fault. I experienced this issue as well. Beat audio... practically a joke... just an audio equalizer, but it can only be used in the Google Music app, and you have to manually turn it on in the notifications menu when it pops up.
Motorola Bionic
Overalls seems to be a decent and enjoyable phone. I haven't really dug into the Bionic as much. I do know some of the issues though of it. Much like the Rezound, audio feedback from the headphones when being used. People have had issues opening SMS messages that make them Force Close and unable to open that specific message.
Sure I missed a few things, I tried directing each one for your use. Something that you need to realize though, 4G eats battery life more than Hungry Hungry Hippos. If you plan on using 4G, you WILL have to charge your phone at work. Using your phone as a hot spot also makes your battery life degrade faster. You also have to pay a charge at VZW to use your phone as a mobile hot spot as well. Luckily, most the phone you will be able to disable 4G when you are not needing the speed. Android 4.0 Ice Cream Sandwhich has been confirmed going to be updated for the Motorola Razr and Bionic, along with the HTC Rezound. Now in dealing with ICS, the UI has it's own built in navigation buttons. So it will be interesting to see how Motorola and HTC implement that into the use of the phones stand alone capacitive buttons. After the first of the year, Q1 or Q2 of 2012 you should see a ICS update. Unless you are into tweaking and want to flash a custom ROM. The Samsung Galaxy Nexus is coming out very soon, days even, and will be packing Android 4.0 with no independent navigation buttons. The hardware isn't the top of the line, but still above average. This thing is fairly big in size, so it probably won't suit you.
I'm not going into the argument, but task killers are useless and are more or less a placebo effect. I had my phone last 4 days with a custom kernel and underclocked. On average I get about 18-20 hours on a full charge with medium usage and no task killer.
