Go to the Practical Sailor web site (URL copied next)
You can order back issues that will give you a wealth of information about both of your topics of interest. Even if their conclusions do not match your best candidate, there is plenty of good information to be learned about technical specs, manufacturers, prices, etc. I've just looked at back issues and the following two should give you what you are looking for.
Best Fixed Mount VHF: July 15, 2005
Handheld GPS Test: October 15,2004