Any honey that has the least amount of wax left in it. The fermentation process works on the wax, producing compounds that result in the hangover from hell. Otherwise, you can use almost any honey in the making of mead. Clover honey is a mild-flavored honey so a lot of folks use it to make plain mead. More strongly flavored honeys will change the taste of the mead and sometimes are better for spiced meads.
However, it is your mead, so use what you want. However, bear in mind that a stronger flavored honey is the single thing that will give your mead its character.
For a nice reprise of the whole mead-making process, check out this site