The Green Star is prolly one of the top 3 juicers out there. It's a twin gear auger juicer and supposedly it has some kinda magnetized voodo mojo in the augers that helps preserve the freshness of juices. It is not cheap though. The Breville is a centrifugal juicer. The plus is that they are fast but they don't do well with leafy greens or soft fruits and it will not do wheatgrass and some of the other neat things like make nut butters or delicious frappes with frozen fruits. It is also cheaper.
Outside of those 2 choices if on a tighter budget I recommend the Omega 2004 which is what I use cept the older 2002 version. It cost is less than half of the Green Star and it has 15 year guarantee. Mine is at least 10 years old. I had a part break recently after 10 years of regular use and all I had to do was email them a pix of the broken part and they replaced it free within 3 days of me contacting them. Omega also has brand new design that is called the Omega Vert 330HD and all the reviews on it are great. Search for it on "YouTube". Actually you can find demos/reviews of all these juicers on YouTube