Normal landscape concrete products require a great deal of work preparing the base. If it's not tamped and absolutely level before you begin laying the blocks you will not come to the correct height, nor will your wall end up being level. Sometimes known as a Rock Face Block Wall these CMU block walls may look like they are easier to build but they're not.
A dry stone wall on the other hand can be laid on a relatively uneven surface. The wall foundation though important does not require laser levels, excessive tamping or complicated elevation calculations. Because the stones are 'real' they come in all different sizes. Therefore it is not too difficult to 'come to level' along the top of the wall and you can come to any increment of height you wish to with just a little planning ahead and clever use of your stone selection.