I would expect to see disguised warships. A warship that looked like the asteroid miners that are already common in the system would be able to get to it's target relatively easily.
An alternative would be an equivalent of dazzle paint, where the sensor returns identify that there is something out there, but some of the information returned (usually heading, range or speed,, as these would cause weapons to be inaccurate) is confused or erroneous. In a high ECM environment, such as when fleets are already engaged in combat, this could be as effective as being invisible.
As for my choice of weapon, it would have to be guided. I would expect space combat to take place at extremely long ranges.
For example at a combat range of 3 times the distance to the earth to the moon. This is four light-seconds away. But due to the time that the sensor light takes to get from the target to the attackers sensors, the attacker is effectively firing at where the target was 8 seconds ago. If immediately after being detected the target initiates a 1G burn (after detection so that the firing ship knows nothing about it), it will have moved 313 metres away from the position estimated from it's state when detected. As it is likely that the ship is smaller than twice this in length, the laser would not only be guaranteed to miss in this case, but also be highly likely to miss at any time, as a ship in combat would be expected to be constantly changing it's acceleration to avoid being hit.
There would be a place for other weapons to defend against missiles and to get first strike against ships that are not evading (although how are you going to suprise them? This goes back to the lack of stealth is space again).
For these I would prefer Lasers as they are almost inertialess, and if a weapon has recoil then firing a particular pattern of missiles against it would result in a particular acceleration which a good captain would take advantage of.
In this combat there would be one method of dazzle which would be very effective. Fit engines in multiple directions, and set them up to give the same signiature whether they are producing thrust or not. Now approaching missiles cannot predict your ships acceleration even at close ranges. This could be enough to cause them to miss.
The really scary form of this combat would happen when the combatants have been fighting for centuries, and relativistic asteroids start hitting planets, having been fired from other star systems.