Are any of the three poisons considered stronger or more difficult to break than the others?

The other two arrise and exist due to Moha or lack of Panna. Hence this is the the hardest. You break this and the other two will break away. You cannot break any or both of the other two while you have Moha.

Yes there are difficulty levels in that. In one occassion Buddha him self said that if any one can give up greed he is one step behind the Nirvana. Most of the steps in buddhism is about greed your right without the right vision we can't see greed. Pain is a form of greed. We try to satisfy our selves with many thing may be massage or sex what ever thing is a form of greed. If you think that this body we have can we do what ever we like with it. Can we stop growing old or stop growing nails. Yeah we can't so this don't belong to us. So we have to see this is as a pain or a greed. We apply many things eat what ever we like this all is greed. The english term greed doesn't give the whole meaning out here. Falling in love with family, wife this is also going under greed. If there is no greed or a task there is no reason for you to exist. If you wish your beloved wife or mom in next birth there you have a reason to exist. So the exact term for this is A CONNECTION. We have to break all connections. In Hinduism or Yoga there is something called Kundalini in there to complete all levels we have to open a chakra in middle of the head. So the step to do that is to remove all you love from mind. After you do that there is no concern for anything anymore. If you get psychic powers from the Kundalini you don't have a reason to use it. You don;t like showing off and you don't want any connection in the 1st place. So you will stay calm.

As per Buddha of Pali Canon (AN 3.68, thanks to @Unrul3r for the reference):

• Aversion (aka anger, aka hatred) has much blame, but is quick to fade away;
• Obsessive desire (aka greed, aka lust) has little blame, but is slow to fade away;
• Confusion (aka delusion) both has much blame, and is slow to fade away.

As explained in commentary on dharmafarer.org:

The Anguttara Commentary to AN 3.68 explains that “has little blame” means “both by way of worldly blame and by way of its (karmic) results”, that is, both in the worldly and the spiritual senses. It goes on to show that lust (lobha) “has little blame”by the fact that there is no social stigma to marriage, although it is rooted in sexual desire (that is, if lust remains within the moral limits). Such lust would not in itself lead to a painful rebirth in lower states. As such, it is less blameworthy in regard to karmic consequences.

This statement may appear strange in view of the fact that greed (lobha) is one of the roots of the unwholesome or evil and that it also falls under the wider-ranging term of Craving, the fundamental cause of suffering. Yet greed is “less blameworthy” than hate in all those instances where the gratification of lust does not violate basic morality and is not harmful to others, as, for instance, the enjoyment of delicious food, sex gratification within the bounds of the Third Precept, and so forth.

Lust, however, is “hard to remove” as it has deep roots in human nature, and is “as hard to remove as oily soot, and a particular attachment might follow a person even through two or three lives”. In a single moment the roots of lust can sink deeply into man’s heart; its fine hair roots of subtle attachments are as difficult to remove as the great passions, or even more so.

The Anguttara Commentary similarly says that “much blame” means “both by way of worldly blame and by way of its (karmic) results,” that is, both in the worldly and the spiritual senses.

Hate (dosa) is more blameworthy than lust and delusions because the results of a hateful act are often immediate apparently, widespread and protracted. Hate is almost always behind killing, acts of violence and life-threatening deeds. As such, hate is greatly blameworthy. However, people often quickly forget such violent acts when they are distracted by other pursuits, especially those concerning living needs, comfort and pleasure: in other words, they are more easily distracted by the drive of lust.

Delusion (moha) is both greatly blameworthy and hard to abandon. It is always at the root of the motivation in the breaking of the precepts, indeed in any evil unskillful act.

Both hate and delusion are regarded as blameworthy in society and have negative karmic results, as both may lead one to rebirth in painful states. Hate, however, is an unpleasant state of mind, and as beings naturally desire happiness, they will generally wish to abandon it. Moreover, by asking for forgiveness from those one has wronged through anger, it is easier to nullify the negative effects of anger in oneself and in others. Delusion, however, is usually deeply rooted in craving, wrong view and conceit, and as such will be as hard to remove as lust.