A full ICMF run will give you enough heat for each level up to about 4-5 (not suggested due to time and lesser cr gain). RJP will give you a little more heat than you need for the first 3-4 levels then gives about the right amount for 5 and maybe 6 (referring to the first level, elite, no deaths only. Increase party size to about 3 or 4 after obtaining level 4 and that should do it). Beyond that, FSC is the way to go. Note that I say this in terms of time and cr because the first level of RJP gives more cr and more heat, making it much more efficient than the first depth of FSC in the -heh- short run really. I believe it's faster too but that depends on much.

TL;DR: RJP full party elite to lvl 5, then to FSC.

There's nothing wrong with getting them all, they all have different uses and slightly different playstyles, but they're all very powerful. Like Bopp said, the best elemental brandish is Combuster because it does the most damage of 3 due to how enemies ride the whole wave and fire just adds the icing to the cake. There's no unpredictability in it, so no worries about charges backfiring on you. It works everywhere with no downside, even in a fire stratum it's superior.

Glacius does a great job saving your hide because it freezes enemies in place. If you have a tough time fighting enemies or you're more tactical, you'd find great use in Glacius, but once you get the hang of things, you'll find this leaving a lot to be desired. Enemies can break each other's freeze, and so can teammates. It can also be considered the most tricky to use cause it can both help and harm you used improperly.

Voltedge is just the brandish in the middle and like Glacius, it can both help and harm with the shock interrupting enemy actions. I can say everything I've said for Glacius here, only shock won't disappear upon impact of an attack.

I could go more into depth, but brandish weapons are the most talked to death weapon there is in the arsenal. Just keep in mind Combuster > Glacius and Voltedge in many situations, but the latter aren't bad at all granted you know how to use them well.

@Halandin With an Electron Vortex, Voltedge is better than Combuster. The shock keeps the enemies clumped into the vortex for follow up attacks instead of Combuster flinging them out. But be wary as Combuster is better than Voltedge whenever you are not using EV.

Maye it's a chance of shock from the EV, so more shock helps? Less likely for the charge explosions to push monsters out of the vortex area? I've seen people use their own brandishes with high CTR to unleash charge attacks on the monsters that they have grouped up with an EV, that's why I was thinking of it.

I already have a Fireburst Brandish, and I wasn't sure whether I should just upgrade that to 4* and wait to use the CTR med Brandish for a Boltbrand someday when I have the krogmos, or use the CTR med Brandish now for a Fireburst then Blazebrand. I'm often using hybrid gear, so sometimes I'm relying on swords for most damage--like in IMF, which isn't so bomber friendly. I'll also switch to a sword or gun for solo enemies or small groups. But, if I'm using bomber gear, a CTR med sword would be better since I wouldn't be using sword-enhancing gear to increase my sword CTR so much. My play style is mostly charge attacks of swords, bombs, and careful setting up of attacks. (Or Gigwatt spam if I'm not doing so well. :D )