Geowls

Newbie to geocaching and found my first cache the other day with a little difficulty. With light tree cover it was telling me that I had poor GPs coverage. Will the new Garmin E-Trex, Venture, or Legend operate better under current conditions. Should I upgrade to a better model? What would one recommend beween these 3 models? What would one recommend for a 11 year old son? Thanks for your input from one who is intrigued by GEOCACHING----------Geowls