My number #1 choice is Timer Bim, because you can manipulate the time to make it a cracker, or a mini mine bomb, making it a deadly versatile weapon.
However, It really depends on what situation you're in. If it's direct confrontation, the Cracker or Implosion types to me are the most deadly and easy to use compared to the other bombs when you have less time to think.
If you're being chased, but not too close, I think "Timer" Bim is by far the most useful, seeing as how you can manipulate how many seconds it needs for it to detonate. If you have several timer bombs, you can set each to different times, some may be 2-3 seconds, others the full 10 and choose the one that fits the situation and just drop it on the ground or somewhere you think the person will pass through.
The Flaming Gas is deadly if you're not in a confrontation at all and you are sure that you won't get hurt if you use it, it's pretty dangerous to use in confrontations as you could
risk burning yourself. The Mine Bim is good if you know an enemy is coming and you set the bim appropriately, but it's harder to use accurately than the timer.
Lastly, I find the Homing Type to be the worst, it takes too long to set up, and it only works if you're lucky enough to see someone and they haven't spotted you. Even then, I would find the cracker type to be more reliable.