the perian is a nice knife, it is heavy though, and also not too grippy. Its shape is awesome, and is a folding version of a fixed blade style that has been used in the middle east (hence persian) for hundereds (if not thousands) of years. It is a very comfortable knife to hold, just one piece of advice, when using the front choil, choke up on the spine (go above the hump), then it melts back into your hand...i found the front choil uncomfortable with my thumb behind the hole.
The paramilitary is a great light weight heavy user without too much blade. It or the millie really depends on what length you want (the paramilitary was designed to bring some of the militarys excelent features to a more city/state legal code accessable size. The manix is very similar in size to the strider AR, though it is smaller, it is still a tough knife. While the military has a longer blade, the manix is by far "bigger" the millie is a not as tall, with a clipped point instead of a dropped one, and its nested liners and open construction add to its light weight design of the millie.
Finally, if you like the persian but want something more heavy duty, check out the Chinnook II. Very similar in construction to the manix, however with a hollow grind for an even heavier blade, and an overal geometry that is similar to the persan's, but with G10.
Otherwise, take a trip over to
www.spyderco.com and just look at the knives.