number crunching on condition and might runes
use noble runes for might stacking condi builds. their usefulness has diminished because of the enhance performance nerf though.
Personally I use boon duration runes instead of might. The engineer has a lot of boons and increasing all of their durations is better than just focusing on the one. I have 2 travellers, 2 monks, and 2 waters. That gives 45% boon duration. + 30% from alchemy line + 20% from omnom cream for a total of 95%. The 20% elixir trait can boost that to 115%; however I prefer to use other traits instead.
With this I get about 10 seconds of stability every 30 seconds (which is awesome!), and near continuous regen, swiftness, and fury. As for might, I roll with FT juggernaught, which gives 10 free stacks (due to boon durations) just for doing nothing. With sigil of battle and fire blasts, I find it easy to maintain 25 stacks.
Now, back to the root of your question. A or B. Well, if you like to micromanage your boons like that, then it’s more rewarding to go that route. If however you just want to play and not concern yourself with that rubbish, then the increase condi dmg from runes of undead (which are also cheap to buy) would be a better option. I use to alternate between the two when I first started with engie and I did have more fun with perma stats like runes of undead. I only switched to alchemy because I really need access to those other boons for my playstyle.