Advanced armour is better. Burning rune should only be used if you already have the advanced armor equiped (which is probably only possible on Veterans because it costs so much loadoutpoints).
I've found it's really inefficient to use any LP on the 40 armour upgrades. They are 10 points to 1 armour, which is the most inefficient gain of stats to LP cost. And 40 armour... bolter headshots do, what, 32 damage? I'm not sure how much toughness reduces the damage, but basically those 400 loadout points allow you survive one additional bolter round, if not two. The extra survival time it affords you is less than a second. May as well just take a master crafted weapon, grenade or wraithcure bundles, more weapon mods, fusion pistol etc. in the veteran loadouts. I definitely 100% would not use burning rune in a standard loadout.
Thanks for the advice. Im currently lvl 5 with the Eldar and just tinker with the loadouts. I mostly play as a Dire Avenger and a Striking Scorpion. Any tips for those? I also like the Dark Reaper - with the Reaper Lanucher. I shoot everything with the Plasma Missle mode. Nice sniping capability and if landed corectly can kill multimple enemies at once. But team kills are a problem :/
I wouldn't write off armor even at inefficient costs as @Rathael says. Yes it become more inefficient point wise but there is no second place in a fire fight. So if your armor gives you the advantage because your enemy needs an extra couple shots and you both have comparable weapons, you will outlast the fight. You also cant use all that other equipment you took instead at the same time. Armor and toughness are passives and just happen to be the core stats for your life. Guns don't get dps increase mods, accuracy might assist but doesn't make it more damage. So the only thing you can really take to increase your staying power in a fight, is your survivability. If you think this is moot, just look at Orks with higher health, make a pretty significant advantage which I think is well worth it. That is probably why I think armor is higher tiers.
Armor for sure, for the same reasons others have stated. The only loadout I use the burning rune on is my Dark Reaper, and that's only because I don't like/play the reaper enough to justify going deep into the tree to unlock the armor. That plus the fact that reapers don't really have a lot of customization options (no weapon mods in game currently) means I have the spare points for the rune.
I use Burning Rune on my Striking Scorpion since the marginal gain in toughness is largely negated completely by melee weapons. Having that extra bit of armor and a lifesteal mod will almost guarantee you to get into melee from stealth. It also will allow you to get out of nasty spots pretty well without risking your valuable hp. With Dire Avenger, I again run the Burning Rune and then as much Armor regen as I can fit. Master crafted Shuriken Cat with some mods, a single grenade, and ammo. The trick with it is using your speed to get to cover, fight till you start taking hits, back into cover, regen armor, fire more, repeat. The more you can extend that 1-2 shot bonous, the more valuable the Burning Rune becomes to you. 1-2 shots can easily become 40-100 over the course of 5 minutes. But it really is about how you play. Putting it on your Elite class extends the armor even further and regens even faster. Those 1-2 hits becomes 3-4. Advanced armor also regens faster too. So suddenly you're taking on several hundred more rounds throughout the entire match and you will definitely see the difference.
Unfortunately burning rune kinda ruins your stealth as a scorpion as well, now, revered banshee on the other hand... that has some potential. Also you really have nothing better to spend the points on there. Dark reapers I personally prefer the mobility enhancement as allowing me to keep up with other eldar (or run away from trouble) but I could really see the burning rune working there on the revered.