It depends on how much higher you need based on the three option you listed. I love higher dropbars so have done all three.

1) If you just need to raise an inch or two, then a good adjustable stem would work. There are several designs and some are better than the other. The best bang for the buck is the Nashbar adjustable stem. Multiple teeth engage so it is a very solid piece. They even come with different length sdo there is even more height adjustment.

2) If you need a little more than a couple of inches, then a riser might be a good option. There are two common heights available.

3) If you need even more height, then you might get a new fork with uncut steer tube. Or use a riser with an adjustable stem.