shooting wise, not much daemons have to pen
AV 14. In fact, I think that's the whole point of AV14, anyways, onto options:
Breath of chaos - 4+ auto glance = 50% chance and vs
LR, you have 1/6 chance to immobilize, 1/6 weapon destroy, and then just shaken/stun the rest which doesn't really do that much.
If you got a squad of 4 flamers for example, you can probably guess 2 glances and really just make it can't shoot everything though it will always have
PotMS
140 points for 4 flamers. 420 for 12 but that's really overkill. 6 for 210 matches the
LR costs kind of close. = 3 glances
Screamers = 4's to hit, 6's if cruising, so 50% miss or worse. melta bomb =
str 8+
2D6 (average around 7) so average 50% glance hit. As it is a grenade hit, you will still just get one attack even on the charge but you do have a decent chance to pen so it's actually one of your better options if you can get in about 4-5 of them. Also since they are jetbikes, you are looking at an 18' charge which isn't bad and even if you mishap, you can still go flat out 24' to make it into place.
at 16 points a pop, you are looking at 192 points for 12 of them. = roughly 3 glance/pens on a charge (with combat movement for the
LR) on average.
Bloodthirster with might + furious charge =
str 9, and it's
MC so
2d6 = average chance of 9+6 = 15 50% pen rate. with 6 attacks on the charge, you got a good shot at some 1- 2 pens with a combat moving
LR. that's a 250 point model to take down a 250 point ish tank.
Fiends are actually a possibility as well with 30 points each x6 = 180 points to dump some 36 attacks, say half hit = 18 hits, say 1/6 for rending = 3 rend
5+6 = 11 + 1d3 = 1 glance out of those 3 rends. This is probably the worst one for the bunch but it is possible is all I'm saying.
Frankly mathhammerish wise, your best point/point ratio would still be to use screamers despite just T4 just cause they are so cheap to grab a bunch. a blood thirster is probably runner up. Skarbrand maybe tied at #2 but mostly #3 just because he costs more than the target and can inadvertently give bonuses to your enemy., flamers are a viable choice at #4, and then fiends if you just have nothing else to try.
Edited 6 into 7 cause I forgot to factor

XD