I can't speak to the advantages / disadvantages of various territories but I can say that a mid 19th century German farmer would make his decision much like you or I make a decision: based upon advertising and "social networking", aka, word of mouth.
Most midwestern states, by 1850, have established or are in the process of establishing state funded offices on emigration^1. These offices commissioned pamphlets, booklets, magazines, and advertisements, and hired agents of state who would travel to chief points of departure in Europe. Acting as official state agents, these men would distribute their material in taverns, city centers, churches, and outside of factories. One such pamphlet, titled "Statistics, Exhibiting the History, Climate and Productions of the State of Wisconsin.", contained the following information in 32 pages:
topographical features, water power, rivers, small lakes, climate, health, geology, lead mines, zinc, iron ores, clays, peat and marl, native animals, fishes, forests, pine region, agriculture, chief crops of 1866 (the total value of which is placed at $69,213,544), live stock, farm products, implements, wages, manufactures, occupations, railroads, markets, population, newspapers, churches, principal cities, lands, surveys, the Homestead Law, land tenure, value of property, government, rights, office holding, rights of married women, revenues of the state, schools, libraries, state institutions, post offices, and routes from the seaboard.^2
Not only did were state governments actively advertising in Europe, railroad and shipping companies very quickly realized that immigrant travel was a highly lucrative business venture. In 1852, The emigration commissioner for Wisconsin, Gysbert Van Steenwyck, noted in correspondence that a docking ship would see:
"a hundred or more agents, runners, and peddlers at hand to make prey of the immigrants."^3
Which was fine by him:
"forwarding agents favored Wisconsin because of the opportunity for high profits in overcharging for passengers and luggage to a region so far west."^4
The business model of railroads at the time depended on immigrant traffic to fund further westward expansion. The Great Northern Railroad, and Chicago, Milwaukee, St. Paul and Minneapolis Railroad provided loans, books, pamphlets, and even visiting agricultural scientists to communities along their main lines in South Dakota and Montana. Establishing farmers was essential to generating revenue from shipping food, tools, equipment, and finished agricultural products. An example advertisement in Welsh, and the type of handbook given to potential immigrants
1 Cf. Richmond Mayo-Smith, Emigration and Immigration, 45-52 (New York: Charles Scribner's Sons, 1908).
2 The Competition of the Northwestern States for Immigrants Author(s): Theodore C. Blegen Source: The Wisconsin Magazine of History, Vol. 3, No. 1 (Sep., 1919), pp. 3-29
3 ibid
4 ibid
