Like so many people, i'm a big advocate of Real Techniques. Most of my brushes are RT; they're soft, high quality and affordable, just to name a few of the long list of their plus points. Sam and Nic have just nailed it. I've managed (with difficulty) to narrow my collection down to my 3 favourites, going for the 3 that i use the most!

The Buffing Brush
Probably the most well known and well loved RT brush and deservedly so. I owned this a few years ago, loved it, lost it, used the Expert Face Brush for a good year instead and then re-bought it and i've barely used anything else to apply foundation since. As the name suggests it just buffs foundation in flawlessly as well as being speedy.

The Multi- Task Brush
Another perfectly named brush. I mainly use it for bronzer but when i'm feeling lazy i use it for the whole works, powder, blusher and even highlighter. Its super soft and is the perfect shape and size for the cheeks.

The Setting Brush
I also use the setting brush for a number of things but i mainly use it for blending in concealer. It is the perfect size to fit under the eye and really leaves a flawless but not cakey finish. I also love this brush for highlighter as it gives you lots of control so you don't go overboard on the glow. As the name suggests it is also great for setting your makeup if you only want a small amount of powder in certain places.

I'm sure most people already own Real Technique brushes but if you don't, get on it now, you won't be disappointed! This may just give you inspiration on the next RT brush you want to own. 
Catherine x