Whatever you purchase, purchase a Garmin. Figure out what features you will use and go from there.

That being said, you can't go wrong with a Garmin GPSMAP 60CSx. I have been using one literally from the first day they were available for everything from SAR & Wildland firefighting to highway travel and it has worked better then any other handheld GPS I have used before or since. The unit gets exceptional reception and is easy to use.

I do have the TOPO software in my GPS, but in reality I find that I typically just end up using it with a paper map for most land navigation. The new Garmin TOPO software on a 60CSx (and many of the eTrex "x" series) is routable, making it useful for over the road navigation.

You can find packages that have TOPO included with just about any Garmin GPS that takes maps, however the only Garmin GPS handheld units that come pre-installed with map software are the newer Colorado and Oregon (specifically the units whose model name ends in a "t" like Oregon 400t), although I haven't been as impressed with the cost vs. usability of these new units (except the Dakota series). The Oregon series are significantly better then the eTrex series, but imho not worth upgrading to if you already have a 60CSx (unless you will be using it more in a vehicle than on foot).