Depends on what you are doing.
If you are doing lots of rounds and need to be very accurate then invest in an automated one like the RCBS Chargemaster. I have the Lyman version and load about 2 rounds per minute (once the brass is prepared and primed).
If you can cope with a 'small' variation then the simple turn a handle and dispense an amount such as the Uniflow measure. I started off with the lee version (much cheaper) and it was reasonably consistent but would take ages of adjusting to get the amount dispensed correct.
If you are only loading a small amount then use some dippers and powder trickler.