There are two general arguments you can make with regards to the preferred method of taxation, one based on morality, and the other based on efficiency.
For morality, it depends on what you consider to be the most fundamental property we can claim ownership of. Is it our labor? Is it our labor applied to land to produce capital? Is it land, which is a factor of production not produced by anyone's labor?
My argument would be that our labor is the primary thing we can morally claim ownership of. An income tax takes away part of that labor directly. The harder you work, the more you have to pay to the state. Hard work is thus penalized and discouraged.
A capital gains tax takes away labor applied to land (in the economic sense of a natural resource of fixed supply) to produce capital. Like the tax on labor, a tax on capital reduces the incentive to save a portion of what you produce, discouraging capital formation and encouraging current consumption (eating your seed corn, rather than saving it until the next planting season, for example).
Only a land value tax does not take away labor directly -- we can, for example, imagine a gypsy tinker who wanders from place to place, working on pots and pans brought to him, but holding no land title. An income tax would reach out to take a portion of the labor from such a person, no matter where he roamed, whereas a land value tax would not. The reverse of this, a rent seeker who does not labor, would seem to be morally more suspect. A person who does not work, but merely expects the state to use force to protect his or her property without payment in taxes, would seem to be at best a parasite on the community. Land tenure secured by the state would seem to be the one thing that -- well, call it a tax, or a user fee, or a rental fee, or anything you like -- could be morally levied. If you control an expensive piece of property, and expect the police to show up when you call, a tax would to reimburse the the state seem to be reasonable.
And as for efficiency, land is fixed in quantity, and a tax does neither encourages nor discourages the amount available. If we tax it at or below the rental value of land, it will continue to be productive, without any reduction in use. Only if we tax high enough that people began abandoning land would we have to worry about negative effects. In addition, since land is fixed in quantity, we do no have to worry about deadweight losses from the tax. This is unlike taxes on labor (income taxes), capital (capital gains taxes), or trade (sales taxes). A tax that doesn't reduce economic activity would seem to be the holy grail of public finance.
Finally, if you think that the community does not have the right to levy a land value tax, do you think that they can use eminent domain to take a piece of property after paying a fair price? Because true ownership by an individual would seem to preclude a superior claim by the state.