Like any other weapons system, the real answer is what is the target? I certainly am not going to "bring a knife to a gunfight", but there are plenty of places where a knife would be the better weapon.
Fixed ground based targets like airfields, seaports and nuclear missile silos is a fairly easy target for Kinetic orbital bombardment systems. First described by Jerry Pournelle (who apparently studies the system as an engineer for Boeing) as Project THOR, these are long rods of a dense metal, with small tabs to provide some terminal control. The project has undergone many different iterations, most recently being revived as "Rods from God" (which is a silly name).
On the wayyyy. What an incoming Kinetic Energy Impactor might look like in flight
If I remember correctly, the system Pournell wrote about used a satellite to deploy a bundle of rods, each about the size and shape of a broom handle. When deorbiting, they moved at @ Mach 25 (which interestingly enough is also the velocity of the metal liner inside a HEAT round as the explosive charge inverts it). With a kinetic energy of @ 3kg of TNT per Kg of weapon, the round could cause severe damage to most systems. More advanced versions were supposed to have sensors hidden in the nose (protected during re entry by a disposable ablative cap) and steer themselves towards ships or tanks, thus taking out moving targets. When you consider a HEAT round accelerating a metal liner weighing a few ounces to Mach 25 can severely damage or destroy a tank, then several kilograms of metal moving at that speed will punch through most normal materials.
For very hard targets, the rods would come in larger sizes. Since the velocity of the round is fixed by orbital mechanics, more mass needs to be added for greater effect. Deep bunkers like the Fordow Fuel Enrichment Plant in Iran would receive strikes from rods roughly the size of telephone poles.
Now physical items like tanks or nuclear missile silos are a very cold war sort of target, and attacking modern 4GW targets like protesting students (who are sending a PSYOPS message to the world via social media) with kinetic energy penetrators from space is likely not going to be cost effective, or have the desired effect on the ground either. Space weaponry can assist in this kind of war by targeting communications and electronics.
The simplest thing to do would be to use an ASAT to disable communications satellites over the target, disrupting many forms of media and communications, but there are plenty of alternative channels, so attacking satellites is unlikely to really shut down that sort of enemy. A large explosion in near space like Starfish Prime would knock out virtually every non hardened system in the target zone, effectively shutting down most civilian systems and any military systems which were not hardened.
Starfish Prime 1
Starfish Prime 2
Starfish Prime 3
Since this is a bit indiscriminate, various nuclear and non nuclear directional EMP devices can be used to essentially send a "spear" of energy at the target, making the damage much more localized and allowing some discrimination and even reuse of infrastructure for your own needs.
The final and virtually non stoppable means of attacking a target from orbit would be to use a version of the Casaba Howitzeror a nuclear shaped charge. These devices convert the spherical energy release of a nuclear weapon into an intense spear of plasma moving at up to 10% of the speed of light, so no target is going to outrun this thing (even a missile or aircraft in flight isn't going to move an appreciable distance between the time of firing and the time of impact of a plasma spear, and the carrying satellite is already moving at orbital velocity to begin with. The linked page provides some calculations on the potential energy release of such a weapon, essentially it is like being struck by the Ravening Beam of Death (RBoD) laser, but without all the heavy and expensive laser hardware.
Conceptual design of a Casaba Howitzer. Illustration by Scott Lowther
The downside of any sort of orbital weaponry is it is itself vulnerable to fairly simple countermeasures. Any small missile capable of rising to orbital hight (not necessarily achieving orbital velocity) can carry a bucket of sand, ball bearings or other debris and release it into the orbital path of an identified enemy satellite. The kinetic energy of impact at orbital speeds would tear the carrier satellite apart, and disable or destroy the weapons within.
Frankly, since you need a versatile weapons system which can strike at hard and soft targets as well as having some capability for self defense, I would go for a strike system carrying advanced nuclear warheads (directional warheads or Casaba Howitzers). Nuke them from orbit; its the only way to be sure.