Is it more efficient..

[Meo]

I think it depends on a few things:

Is your kettle electric or stove top? If stove top, is your stove gas or electric?
Gas stove top w stove top kettle is more energy efficient than boiling an electric kettle (strange but true!) if you fit the burner size to the base of the kettle, ie small kettle on big burner is a no-no.

If you have a gas stove top and you put a lid on the pot, match the burner size to the pot size and use the same amount of water you would have put in the kettle anyway, doing it in the pot will be equally as efficient as using the kettle.

There is absolutely no need to boil the kettle prior to making rice in the microwave, that is excessive

[Snowy Love]

Electric cordless kettle and electric stove - I wish I had a gas stove! Ok, so when I get the gas stove I'll put the kettle away.

[Miss J]

I think I've heard that electric kettles are big energy users so electricity wise it's probably better to just boil the water on the stove. If you're just talking about time saving then using the kettle is probably quicker (if your stove is anything like mine!).

[Kazbah]

Use the microwave to boil the water - more energy efficient than the stove & electric hotplate Plus quicker!

[bon]

I just use hot water out of the tap, and then put a lid on the pot as it boils faster with a lid on. It usually only takes 5 mins or so for the water to boil, and if the water is cold, not too much longer than that.