vayechi

When Yaakov says his final words to his sons,the Shevatim, he tells Reuvain פחז כמים haste like water.  Rashi says on that, just like water flows quickly, Reuvain was quick to get angry, so he lost the 3 main extras that came with the Bechora: פי שנים, כהנה & מלכות the double portion,the kehuna & the malchus. 
The Ohr Hachaim says that immediately the מלכות was given to Yehuda, the פי שנים was given to Yosef, & the כהנה was up in the air until someone deserved it. What was so special about Yehuda & Yosef that they took over the בכורה?
The Posuk says, the ברכה that Yaakov gave to Ephraim & Menasha was that the Bnei Yisroel would bench their children that they should be like Ephraim & Menasha. Why is that? We know when we bentch our daughters we say they should be like the אמהות. Why wouldn't we bentch our sons to be like the אבות? 
The Sefer חכמת המצפון says in the name of רב אברהם זלמנס that being that Menashe was the Bechor, by right he should have had preference in all areas. When it came to the Berachos, Yosef set him up to have Yaakov's right hand on him as he should have. With that came being first for the דגלים, & for the חנוכת הנשיאים. 
But then Yaakov switched his hands & lowered his status to be under his younger brother. Imagine the jealousy that could have caused to have your little brother taking what was rightfully yours. Look at what the jealousy between Yaakov & Eisuv caused, as well as  by Yosef & his brothers. There the brothers' jealousy almost caused Yosef's death! 
But what did Menashe do? Nothing! Not then & not later; he just accepted it without a word! That is why Yaakov wanted us to bentch our kids to be like Ephraim & Menashe. He wanted this Mida to be transmitted to K'lal Yisroel that there shouldn't be jealousy, anger or resentment between us. 
As the Rosh says, "Don't put jealousy in your heart for this is an evil for which there is no cure". What Yaakov wanted was that we should only have love for one another no matter what. 
Chazal say that everyone admitted that Yehuda was fit to be king. Not only that, but we're called יהודים after Yehuda, and he was to have the Moshiach come from him. 
The Targum Yonasan says Yehuda got all of this because he admitted to his wrongdoing with Tamar which was a public Kiddush Hashem.  
Maybe this is why Yehuda & Yosef were chosen. Yaakov is telling us  what's most important:  peace, harmony, & to be able to admit you're wrong or to look the other way when someone hurts you. This is what we want to give over to our children - a ברכה that even though its really hard to ignore when someone hurts you, they should be able to do it because there is no greater ברכה than love & harmony. If we could learn to live like that, then there will be peace and happiness in K'lal Yisroel!