Handwind vs. automatic is a philosophical question and comparing them is like comparing apples an pears.
Nevertheless some remarks which will explain why I came out in favour of the Unitas:
The Unitas originally was a pocket watch movement (Savonette = small second at 6 o´cock) and beats with 18.000 b/h (6498-1) or 21.600 b/h (6498-2).
The ETA 2824-2 with 28.800 b/h is one of the most proven automatic three-hands-movements and is known as an absolute reliable workhorse, nevertheless it is automatic.....
The principle is: the more oscillation you have the better the accuracy of a watch is. The ETA 2824-2 could be considered to be the more accurate movement of those both but the Unitas 6498-1 can be adjusted more easily because of the swan neck fine adjustment which is (always) considered to be a sign of fine finish/high grade movements. If the swan neck fine adjustment is accompanied by a screw balance the movement will not only become an excellent eye catcher, it can be easily regulated to lie level with a regular ETA 2824-2.
The ETA 2824-2 also features the date indication which imho is quite disturbing for the "Marine", seen that the predecessor of the Stowa Marine was a deck watch and date indication was quite obsolete those times. So far the MO follows its pattern the better way.