The best juicer is the one that you enjoy using everyday. There is not one specific juicer that suits everyone. Your ideal juicer is determined by how much you want to spend, if you want to juice wheatgrass, and if your willing to put up with a bit of noise or would rather have a quiet machine that takes a bit longer to make top quality juice.
A masticating juicer uses a gentle crushing action, like our teeth chewing (hence the name) and is said to preserve enzymes and nutrients, creating extra healthy juice that keeps for 2-3 days in the fridge. While a masticating juicer often costs more than a centrifugal one, it will squeeze more juice out of your fruit and vegetables so you'll save money on your weekly grocery bill.
If you hate the noise of a centrifugal juicer then I heartily recommend a masticating juicer, which will gently crush the juice out of fruit, vegetables, and wheatgrass, rather than shredding and spinning them at high speed as centrifugal juicers do. A good masticulating juicer is really quiet. It purrs like a cat, rather than screaming at you like a banshee.
The juice produced by masticating juicers is more nutritious and if stored carefully will keep for 3 days in the fridge.
The downside with masticating juicers is that, with the exception of the newer wide mouth models you do need to chop up your fruit and vegetables, plus they're slower at juicing so it does take longer to make your juice. They are built to last and usually come with at least a 5 year guarantee.
The wheatgrass juicer usually has a narrow feed chute which means if your also juicing fruit and vegetables then they need to be chopped up which increases prep time. With this in mind there are now wide mouth slow juicers on the market which are ideal if you create a lot of different fruit and vegetable juices.