In this paper four fiber-loop-buffer based photonic packet switched architectures are compared. It is done in terms of their packet loss probability and their optical cost under various load conditions for the random traffic model. The recirculating type delay lines are used for the storage of packets to resolve the contention. The architectures use semiconductor optical amplifiers(SOAs) and tunable wavelength converters(TWCs) in the recirculating loop buffer. The architectures have advantage of simultaneous Read/Write and, wavelength reallocation using TWCs in the recirculating loop buffer. Therefore, it improves the switch performance over the architectures using SOAs in the loop buffer. The cost of the various architectures is evaluated by considering FCC (fiber-to-chip coupling) and the WSU (wavelength speed up factor) model.