In Episode II, Jango Fett is seen using two different jetpack models. On Kamino, he uses a Mitrinomon Z-6 (note the exhaust nozzles on the side):
On Geonosis, he uses a Merr-Sonn JT-12 (note the exhaust nozzles underneath):
Obviously, he had to switch to the JT-12 on Geonosis because the Z-6 was destroyed on Kamino during his fight with Obi-Wan. However, Wookieepedia's article on the JT-12 claims1 that
Fett continued to alternate between his JT-12 and Z-6 models, until the latter was destroyed during a battle with Obi-Wan Kenobi on Kamino.
Why did Fett use two different jetpack models? Why not just keep multiple Z-6s or multiple JT-12s and only use one jetpack model? Is the Z-6 better in certain situations and the JT-12 better in others?
It is tempting to assume that the Z-6 is superior because Fett's JT-12 is not equipped with a missile on Geonosis, but The Clone Wars shows JT-12s equipped with missiles:
1 Wookieepedia's claim that Fett "alternated" between the jetpack models is uncited, but screenshots from Star Wars Bounty Hunter confirm it. If memory serves, he used the Z-6 when he was equipped with the jetpack-launched missiles, and the JT-12 when he was not. But this was likely a game mechanic or perhaps just following the portrayal in Episode II, since the JT-12 was capable of carrying and launching a missile as well.