Bandos Spiritual Mages have the highest hitpoints out of the 4 types so will generally take longer to kill. If doing them for a slayer task you will get more slayer xp per mage as well as more combat xp than the other 3 types of spiritual mage. They are rarely killed, most people tend to stick to Zamorak and Saradomin mages, but Bandos Spiritual Mages are still very good to kill, they are almost always available to kill and you get that extra xp per kill.
The Bandos Spiritual Mages are just as dangerous as the other mages in the fact that prayer is a must, the monster examine is actually wrong for these as their max hit is over 15, i've been hit a few 20s while fighting them without prayer. I've found the spot just south of the Bandos door (inside the stronghold) to be a good place to kill them, there are two mages here quite close together. Try killing these two on a busy server (1500-2000 players) as it speeds up the respawn rate and you shouldn't have to wait long in between respawns, if at all.
Most people use melee to kill spiritual mages, range can be just as good though. If ranging using a fast weapon such as a short bow, throwing knives/darts etc perform best.