Really depends on your intended use/budget. Gaggia makes good machines, but can tell you from experience the smallish boiler they use can be a limiting factor to an extent. They do recover fast, but they also deplete quickly during an extraction. The NS Oscar is a heat exchange machine and will require knowledge on your part on how HX machines function and you will have to do flushes often to balance temperature at the group as is the case with a lot of HX machines. With the Oscar you will be able to brew/steam simultaneously, which you CAN'T do with the other 2 machines listed as they are SBDU (single boiler double use) designs. Downfall with HX machines is that in order to boost steam pressure (if needed) you must raise boiler pressure via the pressurestat, which affects brew temperature. Last, but not least is the Silvia. I actually just scored a killer deal on a Silvia/Rocky combo via Craigslist and am totally satisfied with it thusfar. People whine quite often about the Silvia being tough to master because of the thermostat setup, offset group design, etc. Truth is most people just don't have enough skill to master this true semi-auto beast. It is a very non-forgiving purist machine that requires effort, skill and determination to get a handle on, but will reward you with great espresso and longevity. Also, don't believe any negativity on the Silvia steaming power being weak/slow as that is definitely not the case.
