Tough question, but i agree it's very dependent on the current situation.
Generally speaking when enemy bubbles are on choke points or a ranked objective (happens alot from my experience), i'll always try to use the opportunity to catch my opponents of guard by for example throwing a bomb on a bubble near an enemy or target the special user (who is still in his/her special animation) if the opportunity arises.
A side-effect of bubbles is how they obscure the vision of both you and the enemy, wich can be used in your favor, reason why I prefer a stealthy approach on enemy bubbles.
I very rarely bother to fight the bubbles directly for multiple reason:
- Your vulnerable to an enemy ambush if zeroing in on a bubble.
- Can lead to stalling the match, especially dangerous if the enemy has the objective
- more personal: It's huge gamble to focus on the bubbles in solo que due how you can't tell how many teammates will also do the same, you really want to overpower bubbles together rather then alone.
Another thing important to now, if a bubble explodes near other bubbles, those bubbles wil likely explode too possible making your effort on 'canceling' some bubbles futile.
Of course, this makes it also always risky as you can easily end being blown up yourself.
if the bubbles are in a cramped space i rather wait for the enemy to explode them and directly attempt to take back the ground, possible using subs or countering with a special of my own.
One thing I noticed is that players in ranked focus on bursting the bubbles directly rather then waiting and use them as a 'buffer' or something, so i'm not at a risk of losing precious time waiting on the bubbles to explode.
Situations were i do attempt to overpower the bubbles is when either the enemy is pushed back or splatted but their bubbles remain or when my team actually focus on a bubble and they are low on 'health' anyway.
But both of these are on the rare side.
Sorry i made this pretty long (never typed the word bubbles as much as now), i'm learning how to use and deal with it myself and ended up thinking alot about it. :p