Legacy vs suitetax depends on their specific requirements - if not very advanced legacy can be very easy to deal with but it has some issues, especially with several tax registrations per entity - the 'automated' reporting capabilities are also grossly overstated, Germany localization goes far beyond that intl tax reports bundle. Suitetax has similar localization bundles and should be considered 'future-proof' I'd say (legacy will eventually be end of life I'm sure.) It is worth noting legacy is easier than suite tax to 'hack' but its usually not recommended unless you are really strong with the reporting requirements. I have yet to see a 'pretty' report come out of intl tax reports bundle that was actually in a submissable state, and that goes for Germany and UK as well.