I’ve been wondering which one would be better to have, Lazuli fixer or Aerlan fixer.

I’m neither right now, but I’m going to change to one or the other eventually and would like to know what the tradeoff would be from those who have experience.

Does a Lazuli fixer give 20% hull for the base ability? Or just the 10% any fixer or Lazuli would?

20%

No its only 10. You don't count the lazuli part for the base buff.

I not either of those races / profession's either but i had this discussion with lone.lycan before they left the forum

anyrate, as anarelen fixer you get +30% defense and +30% hull --> ~ +47% defense with Velox / ~ +66%defense when attacked if you have trinity , and ~ +41% hull with kalviums. upside you get a good hull boost and your defense gets pretty nice as well, downside is, as stated people / NPC's can debuff you.

Flipside, as a Lazuli fixer you get +50% from race and +30% from fixer + another 10% with kalviums, and since the math is cumulative, and not linear you end up with something larger than you think:

1 + 50% = 1.5 --> Lazuli
1.5 + 30% [ 1.5 * .3 + 1.5 ] = 1.95 --> fixer
1.95 + 5% [ 1.95 * .05 + 1.95 ] = 2.0475 --> Kalvium 1
2.0475 + 5% = 2.149875 --> Kalvium 2
2.15 - 1 (initial 100% hull) = ~ 1.15 or 115%

it equates into how much of an energy sink you want to be and how big your crew is really.

And he's over my shoulder right now saying how you've totally missed the question being asked (bugging me to no end until I agreed to tell you that. OUCH!! *rubs shoulder*)