This is a debatable question because each has its own advantages and disadvantages but the important thing is that wireless broadband is 100% portable while fixed broadband is fixed at your homes and offices. Wireless is simple and free to set up while for fixed broadband you need proper connection and initial installation.
Also fixed broadband gives limited multiple usage while the other gives multiple usage. Device should be able to run for 4G, 3G etc. for fixed broadband while for the other device compatibility is not necessary.