the Greenstar is probably the best from what I have read and researched, but not in a position to afford one at present.
The Jack LaLanne juice extractor is probably the best in terms of quantity of juice for a Centrifugal type, as it has a patented method of superior extraction. It is very easy to clean, effortless to use, with a very large entry point for the fruit/veg', so no need to cut everything up into smaller pieces, AND you can juice as much or as little as you would like, without having to stop and clean it to continue juicing.
Make sure you mention my name to the salesperson if you buy one, as they will send my commission cheque in the post!!!!