Gentle Friends,
First of all, I want to acknowledge that one should collect what one likes. If one of the three particular series (RTA, Egyptians, Crusaders) under discussion "grabs" you more than the others, then you should collect that one.
As I have said many times, my collection is characterized by diversity, which, translated means I have many different interests (or absolutely no will power). I have figures displayed from numerous times, places, and events. When guests visit my home for the first time, I have noticed that they usually are drawn to one of three groups of figures I own. These three groups, in no particular order, are: 1) connoisseur figures (medieval knights), 2) Ancient Egyptians, and 3) Delhi Durbar (Beau Geste, Britains, Marlborough). It is interesting to me that people who do not collect toy soldiers or who have not seen many toy soldiers single out the Egyptians as one of their favorites among the choices I am able to present to them. I think their reactions testify to the compelling and impressive nature of the Egyptian figures.
In short, I do not think you can go wrong collecting any of the three lines of figures, especially if one line attracts you more than the other two. However, the great mysteries surrounding the Ancient Egyptian culture, combined with wonderfully sculpted and painted figures, seem to really touch many people.
Warmest personal regards,
Pat