I have owned the Yaesu 857D and I just became the owner of an Icom IC-7000 that I replaced an Icom 706MKIIg with. I am becoming familiar with the 7000 with the intent of writing a detailed review of it in the very near future. I have not owned the Kenwood you mentioned.
The Yaesu 857D is a good mobile HF/VHF/UHF radio. However, the screen is very small for a mobile, which may be important to consider. The menus are a little goofy, although you can get use to it.
My initial impressions of the Icom 7000 are very positive. The screen is big for a mobile and very crisp and easy to read. You can see a lot more of what is going on with the rig because there is more display room. It uses DSP at the IF stage instead of at the AF stage like the 857D. This means that they can also use the DSP to affect filter width and shape and they provide you 3 filter width presets. The DSP also provides a manual notch filter function. There are a bunch of things that the IC-7000 can do that the 857D cannot. However, at $500 more than the 857D, it should do a lot more, too.
In my so far limited use of the IC-7000, it seems like clearly the best mobile HF/VHF/UHF rig on the market. It makes for a fine base station rig, as well...as long as you don't plan on doing a bunch of interfacing to external devices (not enough ports on mobile rigs).