Ok, I guess it's up to me...
I've only worked with Tunelab pro for a little, and took a class once, though I keep up with that list as well. I used RCT for quite a few years in a laptop version.
There are two versions of Tunelab. The newer one is more user-friendly, though less adjustable. Both RCT and Tunelab for Pocket PC are very similar to their laptop versions, and through the work of their develpers, continue to improve. They both share a similar automated sampling routine before starting tuning. (You play a single string, the machine does all the listening and calculating) Tunelab displays the raw data to allow you to accept, or toss out a sample, while RCT requires three samples of the same note to assure sample quality. (RCT sample notes are fixed, while Tunelab allows for additional sampling, like at the break, if you choose.)
After sampling, Tunelab allows for manipulation of the tuning curve via 4 adjustments, and choice of what interval type for each zone. RCT offers 9 built-in types of tuning preferences, as well as a custom adjustment screen. Both machines use graphical representations of the tuning curves and interval widths to assist with the tuning calulation adjustments.
Due to the choice(s) of where different partials are to be used for tuning in different ranges of the piano, final tuning results will differ from machine to machine. You will find users very happy with both systems.
The displays are different, RCT using a spinner, along with left and right movement of the spinner to show notes far from pitch. Tunelab has a split-screen, showing moving bars for fine tuning, and a spectrum display which can show either a multi-partial, or single partial wave for any note. In fact, with two string sounding, you will see both notes represented as two separate peaks until the strings are very close to tuned.
Both can save huge numbers of tunings, and overlay temperament offsets to the tunings. (There may still be some differences here in the Pocket PC versions)
RCT seems to have an edge with its pitch raising mode, it is possible to get very close to a single pass pitch raise being the same as a fine tuning. Tunelab, with the spectrum display allows for mute-free pitch raising, giving it the speed advantage in two-pass tuning. RCT allows for color change option to the spinner, giving it the "cooler" look.
Tunelab can be downloaded from the web for a test-drive, free of charge from: http://www.tunelab-world.com/
RCT must be purchased, and there is a hardware "key" to assure that it is only used on one machine at a time. http://www.reyburn.com/
Does that help?