I personally think SMN is the most powerful job in the game right now...for several reasons:

1) Very good ST dps, top AoE dps; 2) almost absolute mobility, second only to BRD/MCH in this regard (half of the time you can run around because you're either in DT or you need to weave stuff so you're using ruin 2/4. Also trading 20 potency in order to move when needed is no big deal); 3) utility! Radiant shield+devotion are more valuable than hypercharge. Also, resurrection is a nice bonus; 4) synergy with other dps' buffs (you can easily line up DT and baha with tricks/stratagem with a little practice); 5) flexibility: unlike other jobs that have a very restricted window when they can use their burst/oGCD abilities, SMN is much more flexible in how it can use AF stack, DT and bahamut. This basically means that it can easily delay/hasten the use of its resources to take advantage of any possible scenario.

Another important thing is that SMN is the job that benefits more from downtime. Downtime=more AF, and since SMN's burst is so strong, SMN benefits from downtime relatively more than other jobs. Which is why SMN is so obscenely OP in both ultimate fights and it's very strong in kefka (first part). Still, it's not like BLM is in a bad position. Granted playing BLM optimally is much harder, a good BLM is still a valuable asset. I feel bad for RDM though...poor thing.