When to use which style of balloonion attacking?

Not sure how to answer exactly but her are some formations

The Daddy Maneuver (named after the former Daddy)
This involves a V formation. Best done if you have some desired targets with rage of said v. Make a v in a corner of the base, drop 2 rages on your flanks almost immediately. Drop a 3rd if needed when the two sides of the formation meet.

When to use - this is ideal for going for the core of a base.

Simple V Formation
If you don't want to go heavy on spell usage, then use the V formation but just drop one rage spell on the center of the V. This works best if the V is naturally converging on said rage spell. Again this is still good for penetrating bases.

1-2 Attack
Basically this involves attack in 2 waves. This is best for ant-hog designs or other bases that have cleaver AI pathing to get Balloons to wander. Similar to the first 2 maneuvers this is designed to get to the core. Deploy 1st wave of balloons, drop a rage near the center (the way I do it). Time this drop so the first wave hits important defense structures but also so the second wave can ride the last bit of the rage to intended targets. Wait for 1st wave to destroy at least the 1st layer of defensive buildings, then promptly deploy 2nd wave. If done correctly, the second wave should head straight forward.

Simple Straight Formation
Best for exposed AD on the outer layer. Ideal if the center has X-bows that are pointed down and the base has a broadside. Just drop a large line of balloons. Drop rage/heal as necessary.

Fan Formation
Deploy balloons in a line, but deploy minions in the center. Best used if the core is weak, especially if its lacking wizard tower cover. Called a fan formation because the minions will tend to fan out, due to the buildings the balloons cleared

Sandwich
This involves at least 1 dragon. Deploy Balloons and a handful of minions on each flank. Deploy dragon/dragons in the center (2 is recommended), if need be wait until dragon's AI would take it to the core. Basically the dragon and larger part of your attacking force will be sandwiched between the two balloon flanks. This requires that these units get deployed very quickly, at least ideally. Note: You still deploy balloons in the center.

Collector/50% Raid
Deploy balloons like giants, very quickly deploy minions behind. This requires an army of 12-16 balloons instead of 20-24 (can still manage with 20, but 24 means you won't have enough minions - more than likely). Spread out balloons all around the base. If don't quickly, chances are you will inflict the 50% on the outter rim of the base. This works best for collector style raids on base that centralize the heavy defenses. Heros/CC troops help to pick off areas where you won't have enough troops to deploy.

Awesome Guide - http://forum.supercell.net/showthread.php/181958-UnitySharp-s-Farming-Guide-for-TH9-How-to-Max-TH9-Fastest-without-Gems?highlight=guide

Other than that, I'd just recommend mastering each style. Honestly if you excel at each type then few bases will genuinely be off limits. Here are some big problems though

Duel Infernos - these will just destroy minions in seconds, and they aren't hard on balloons to boot

Heavily Centralized AD - honestly these aren't a instant skip but are very risky so there tends to be better targets

Centralized AD and Wizard Towers - its best if your balloons can take care of the 1st line of wizard towers. This way your minions will be more effective. So if both structures are out of reach, its going to be a tough go

3 X-bows all pointed up - Ideally you want some of these puppies pointed down. Depending on your trophy range you should be able to find a nice target that doesn't have the all pointed up. Its not the power of the X-bows really, its just that every little bit of DPS adds up.