Heya,
Handheld VHF radios are a good thing to have, and I'm glad you're looking into getting one. There's a few things you may want to be aware of if you haven't already read up on them. There is a big difference between being water-resistent and waterproof. Water resistant means the unit should function for instance if it's on the deck of your kayak and gets some water splashed on it. Waterproof means the unit should still function if it's dunked under water at a certain depth for a certain amount of time. A JIS7 rating means the unit is waterproof. Personally, I wouldn't go for anything with less than a waterproof rating for use on a kayak. Along those lines, consider either using the radio in conjunction with a dry bag like an AquaPac or such, or keep some type of leash attached to it in case of mishap. A few radios have been lost by kayakers who have flipped over or just plain dropped them while handling them. In addition, some radios will use LI-Ion batteries which will last a long time as their primary power source. Some radios use a high energy battery which can be separated from the main body and a battery pack that usually uses AA batteries can be installed in it's place. That way if you're on a trip and your battery pack goes south, you can use the AA route as a backup and have a functioning radio. Some rados will also have other frequencies or channels in the for say FRS's or Family Service Radios like the Cobras and Motorolas and many other brands. Most decent radios come with a 3 year warranty with them. And the prices are around $100-$200 for good ones.
As far as brands go, thats a hard one for me. I have always use Standard Horizon radios besides Motorola's. I like the Standards, but there are other brands like ICom, Uniden, Raytheon and a bunch more. I currently use one of the Standard HX350S Radios and it's worked out well for me, but they are by no means the only good brand there is.
If you have some reading time left in 'ya, here are some links to user reviews that may be worth looking at:
http://www.nextag.com/best-vhf-hand-...io/search-html
http://www.boatus.com/husick/c_hheld.asp
http://www.powerboat-reports.com/sample/vhf.html
http://www.bizrate.com/marineelectronics/
Hope these can help,
Perry