I would say each has it's own advantages and disadvantages.
On an inclosed fire you wouldn't want to be using a Haltron or Co2 as they are not breathable.
Looking at cost, size and weight, I think a two-stage approach is probably best. Small extinguishers for the initial fire. If it gets large enough to use a big extinguisher, you probably aren't going to care about the mess it makes. Also, as long as you clean up dry-chem it's not a problem anyway.
At concentrations greater than 17 percent, such as those encountered during carbon dioxide fire suppressant use, loss of controlled and purposeful activity, unconsciousness, convulsions, coma, and death occur within 1 minute of initial inhalation of carbon dioxide (OSHA 1989, CCOHS 1990, Dalgaard et al. 1972, CATAMA 1953, Lambertsen 1971). At exposures between 10 and 15 percent, carbon dioxide has been shown to cause unconsciousness, drowsiness, severe muscle twitching, and dizziness within several minutes (Wong 1992, CATAMA 1953, Sechzer et al. 1960). Within a few minutes to an hour after exposure to concentrations between 7 and 10 percent, unconsciousness, dizziness, headache, visual and hearing dysfunction, mental depression, shortness of breath, and sweating have been observed (Schulte 1964, CATAMA 1953, Dripps and Comroe 1947, Wong 1992, Sechzer et al. 1960, OSHA 1989). Exposures to 4 to 7 percent carbon dioxide can result in headache; hearing and visual disturbances; increased blood pressure; dyspnea, or difficulty breathing; mental depression; and tremors (Schulte 1964; Consolazio et al. 1947; White et al. 1952; Wong 1992; Kety and Schmidt 1948; Gellhorn 1936; Gellhorn and Spiesman 1934, 1935; Schulte 1964). Part I of Appendix B discusses human health effects of high-concentration exposure to carbon dioxide in greater detail. -
http://www.epa.gov/ozone/snap/fire/co2/co2report.htmlThe advantages of Halon 1211 (most common I think) is that it leaves the extinguisher as 85% liquid and 15% gas. It is also used in areas where there will likely be people as Halon is relatively safe to breath. The problem is the production of Halon ceased on January 1, 1994, under the Clean Air Act. Halon is a CFC. Haltron on the other had is discharged as a liquid. It is environmentally safe. I've read that Haltron is about 1/2 as good as Halon 1301. Haltron is a replacement for 1211, IIRC. The best is 1301 which is a gas.