The 40 companions all bring something extra to the crew skills. Everyone has a two bonuses that apply to two crew skills. Every companion has it’s own unique bonuses which gives each class different options.
There are two types of bonuses; Efficiency and Critical.
This bonus affects the time it takes to complete a task. It might seem nice to be able to craft items or gather mats faster, but in reality this does not increase the profitability in any way, unless you are online 24/7 and assign tasks to companions as soon as they become available.
The critical bonus increases the chance of the task to have a higher yield. For mission tasks this will award artifact materials, schematics or gifts. For gathering skills it will simply add more materials. Most crafting skills will add an augmentation slot to the crafted item, with Biochem being the exception as stims, medpacks, and adrenals cannot have such slots. Instead a critical craft of these items will yield an extra item. Implants will still get augmentation slots.
The critical bonus is more profitable than the efficiency, so try to aim for crew skills with those bonuses to your class when selecting skills. The below table shows the distribution of bonuses. For each of the two types there are 3 tiers. For efficiency the tiers are +5, +10, +15 and for critical they are +1, +2 , +5. Always try to go for the highest critical bonus if possible.
Republic vs Empire
If you were to have one of each four classes for each faction how would you select your crew skills based on profitability? It is hard to determine what is most profitable from server to server but here is the selection I would do if we assume all servers are the same.
- Jedi Knight: Biochem**, Slicing, Treasure Hunting (+8 crit)
- Jedi Consular: Scavenging++, Diplomacy+, Underworld Trading+ (+5 crit)
- Trooper: Armormech**, Scavenging++, Diplomacy+ (+12 crit)
- Smuggler: Armstech**, Bioanalysis+, Investigation+ (+9 crit)
- Sith Warrior: Synthweaving**, Bioanalysis+, Treasure Hunting (+12 crit)
- Sith Inquistitor: Archaeology+, Scavenging+, Underworld Trading++ (+9 crit)
- Bounty Hunter: Biochem**, Bioanalysis+, Treasure Hunting (+6 crit)
- Imperial Agent: Armormech**, Diplomacy+, Underworld Trading++ (+9 crit)
*: Supported by one other crew skill **: Supported by two other crew skills +: Supports one crafting skill ++: Supports two crafting skills
It is clear The Republic has a lot more synergy in crew skills between classes if you look at critical only and favors crafting skills whereas The Empire favors mission skills. You could even change out Bioanalysis for the Sith Warrior and go with Investigation to diversify.
It is also worth noting companion affection impacts Efficiency and Critical as well as task yield/success so make sure to max their affection. This is also why you should avoid using the droid you get with your ship on mission tasks at all if possible, as it does not have any affection and will have a higher failure rate than your other regular companions.