Plus/minus on all the units
PLRF25C - Small and light, excellent range capability, good connectivity. Downside is monocular viewing, high price > $11K
Vector IV or 21 - Bino is a much better observation device, outstanding range cabability, good connectivity. Downside is more weight/bulk.
Steiner - Bino with good ranging. Downside is bulk, limited connectivity, range data only, no DMC
Moskito - In between size of bino and PLRF, but has a built-in image tube for night use, good connectivity, excellent range ability, DMC. Downside is monocular view at 5x day and 3x night.
The Vector and Moskito can have an add on lens to increase magnification, with the added weight and bulk. 10X for the Vectors and 8/5 x for the Moskito. Lack of a DMC is a significant factor for the Steiner, IMHO.
Connectivity depends on what your needs are, if any. Depending on target size and location, beam size is an important factor. I tend to go for the tightest beam size if at all possible. That tends to drive cost quite a bit higher though, as noted by the PLRF and Vector 23 retail price.
Note that the Vectronix units have many measurement features, like the distance and azimuth between two points, multiple object measurements, horizontal distance and height difference just to name a few. They are all NVG compatible if that matters.