A combination between two elemental types, which one is optimal?

[shadowskinC]

Been trying to build a blaster sorcerer lately, for a Kingmaker campaign. I decided to take elemental bloodline so that I can convert the damage type when needed. So which of the spell and elemental convert type combination is more practical overall?
Obviously, a result can be concluded from here that a combination between Electricity and one of the other three types suffers the least from multiple resistance.
Acid+Electricity is the safest bet here, when considering elemental types. However, between these two elements, the only specialized spell I can think of is Lightning Bolt, which is far from great when considering blasting.
Taking spells into consideration,then fire comes in to sight. We got burning hands, scorching ray, fireball, and fire snake, all decent options throughout our career. The downside is, obviously, a slighter chance to avoid resistance/immunity, especially when facing outsiders.
Cold is also a good option, due to the none-save effect of rime spell. Haven't built a character based on cold though, so I'll skip the part of detailed analysis here.
So did I miss out any option? Spells, feats etc. I'm quite determined to take non_Crossblooded sorcerer though, due to character concept.

[SheepishEidolon]

Well, if you really want to focus on blasting, you could take a kineticist (with a second element at level 7) and enjoy causing elemental havoc all day.

But, you seem to be set on sorcerer already. There are multiple options to change the energy type of a spell:

1) Elemental Spell metamagic rods. They are cheap for their power (to the point of slightly overpowered IMO), but you have to find them.

2) Elemental Spell as feat(s). Take one to four of them - while feats are somewhat rare for sorcerers, the increased flexibility might be worth it.

3) A single level of wizard with the admixture subschool. With an Int of 10 or 12 you can change the energy type three or four times a day. Delaying your sorcerer spell progression by a level is a steep price, but you will gain a few more spells per day (and known) from wizard, boosting the weak start of sorcerer. You might want the trait Magical Knack to compensate the caster level loss - or, as a half-elf, Bifurcated Magic (additionally adding +1 CL to wizard).

If you want a complete list of sorcerer spells, you can check out this one. There are a few acid and electricity spells (press Ctrl-F to search for the energy type name), but yup, fire gets the most and (probably) best offers.

Finally: It's Kingmaker, so don't worry about energy resistances and immunities too much. In the worst case of everything being immune to anything, a sorcerer can still be helpful with handing out haste, heroism, blur / displacement etc. to their mates.

[Cavall]

You're out in the woods. Take fire

[Ryze Kuja]

In Kingmaker, you'll face lots of humanoids, trolls, animals/plants/fey, and a few undead. Fire and Acid do pretty well the whole game.

Side note: Almost everything in this campaign have crap for Will saves. So you're looking to shore up some of your utility, enchantment/illusion spells and Slow can do some serious work even without Spell Focus.