In my humble opinion as a former guide and life long hunter:

The toughest trophy is a record book whitetail, bull elk,goat or bighorn on public land unguided. There are probably some extreme hunts in other parts of the world that are as or more difficult but that is beyond my experience to comment on. Almost anyone can drive around in a Land Cruiser and shoot animals. But not everyone has what it takes mentally and physically to plan, pack and execute a hunt in a draw only, public land area (especially a wilderness area) and take a record animal.

But everyone has their definition of a trophy. The way I see it, as long as you had fun, made some memories, spent time with the people you love and your doing what you love, a rabbit could be the greatest trophy of them all.