Best use of Combat elixers?

[Rune Priest Ridcully]

So what units are people using combat elixers on and which upgrade are they using?
I'm thinking bikers with either increased toughness or movement, or maybe a lord with movement or strength.

[WarriorFish]

I'm also interested in knowing, I've not had chance to make use of them sadly I reckon that squads would benefit the most, something to give them an edge and get more from it. The better squads are tempting but might make them too much of a juicy target, I was originally wondering if a CSM squad would be the best place to start experimenting?

[Marshal Loss]

Movement is almost never worth it, particularly on a unit that is already fast. I generally take the toughness boost as it tends to be the most impactful of all the choices, especially if you're playing against opponents liable to throw S4 or S5 shots at your infantry (and on Terminators & Possessed for example it will stop overcharged plasma from wounding you on 2's which is incredibly useful). The bigger the unit the better the target, so a larger squad of Terminators/Possessed/Noise Marines tops my list of potential drug addicts. I love that with only a couple of CP investment a relatively cheap squad of Terminators can be such a reliable anvil.

[Maschinenpriester]

I usually use it on terminators, chosen or noise Marines.

In 8th it made big blobs of noise Marines pretty nasty. But now they are too expensive. So for now I would go with terminators.