Spike LR is much better. Fire & observe mode makes all the difference. Basically when firing Javelin you have to see the target to lock on(that also endangers operator of enemy fire, where in case of Spike you can hide safely behind a hill and engage targets BLoS) which limits the effective range to about 800-1500m(typical LoS in eastern Europe) and after you fire you can't deliberately miss the target so there is a high chance of destroying own vehicles. Can you tell a difference between T-72B3 and PT-91 at a distance of 1-1.5km? Include bad weather conditions which would radically decrease visibility. On the other hand you can fire Spike manually and make sure you will hit enemy vehicle, not yours or redirect missile into more important target you have just detected. You don't have to see the target before you fire and you can make use of the full range of Spike. That's my short take on this. I'm sure that @Militarysta can elaborate more on this.