OP, There are many things to consider. The fancier hitches tend to have tilt in 2 axis and have lots of adjustability to raise or lower the hitch head and move it back and forth within the bed of your truck. Have a head piece that articulates will help prevent binding and smooth out the ride down the road. Then you have the actual mechanism for latching onto the kingpin itself. The fancier hitch tend to have 2 jaws that wrap around the kingpin and take up all the slack as it engages. The cheaper units tend to have a sliding bar that has a bit of slack and makes for jerky rides. Then you have the in-between hitches, such as those with a J-hook or other latching mechanisms.
As others have said, you have to look into your own circumstances. A slider hitch will buy you more maneuverability in the extremes, but with a front cap that is scalloped for a short bed, there are few circumstances in which you will need it. Another, equally pricey solution, is the sidewinder product from Reese. This moves the articulation point to the pinbox under the 5'ver and you get full articulation like the 8' bed guys as well. I think the keystone scalloped heads are advertised to provide 85 or 88 degrees of turn, while the sidewinder or a slider can buy you a little over 90 degrees of turning radius (like 95 or maybe even 100 degrees). Again, you would only need that in some very extreme cases, and the gain is small with the modern scalloped front ends.
