I have been asking myself the same question up till recently. Juicer shopping is a chore. The number of features and prices of juicers to compare makes choosing a juicer a difficult buy.
I recently discovered the best juicer comparison site on the internet which has made it easy to choose the right juicer. It not only has heaps of juicer reviews to read but you can add your own on any juicer. Best of all if your favorite juicer is not on the site you can add it and leave your own review.
The other great site I have seen with regard to any whole/raw food health & fitness appliances is Vitality4Life. They seem to have a great range of products shpped around the world at really good prices.
I have an Oscar Vitalmax now and have never been happier with a food processing appliance :)

These are both dead links, as they are products that have not withstood the test of time. I would recomend the 800JEXL, by Breville. This is their Elite model that boasts 1000-watts of pure juicing power. If you are patient I would recomend another model, however if you desire efficiency and speed then this baby will make 8oz of juice in about 5 seconds.

If you are looking for a cold press jucier (a.k.a. masticating juicer) you are welcome at http://bestpressjuicers.com/. There are a lot of decent reviews, so you can pick a juicer which match your needs.

Omega J8003 Masticating Juicer is the best juicer.
Why do I LOVE the Omega J8003 juicer?
Three simple reasons:
1) It’s affordable($206.99)
2) It’s a slow-press masticating juicer that makes high quality juice and can easily juice wheatgrass & greens too
3) It’s easy to clean and re-assemble
 

I will recommend you buy masticating juicer instead of a twin gear juicer. One of the best things about them is that they are affordable juicers. You don't need to pay a huge amount to buy this juicer. All masticating juicers give a more nutritious juice by breaking down the fiber of the fruit and vegetables more thoroughly, releasing more nutrients into the juice