Gabriel Stoyanov, 21, was attacked by the youths after getting off the 181 service in Bromley, south-east London, late on November 4 last year.
The business management undergraduate had been out drinking with a friend and, after they got on the bus, he attempted to engage with the defendants, now aged 15, 17 and 18.
The defendants got off the bus two stops later and went to the home of the 17-year-old.
They armed themselves with weapons and lay in wait for the victim outside a takeaway restaurant.
CCTV showed Mr Stoyanov come out and back away as he saw the defendants.
Alfie Kibble, 18, swung a motorcycle chain at him – but missed – and the 15-year-old lobbed a bottle before a 17-year-old stabbed the victim in the chest with a knife.
The youths ran away and Mr Stoyanov was rushed to hospital where he died the next day.
Prosecutor Edward Brown KC had told jurors: “He was killed for being little more than drunk and annoying, perhaps very annoying.
“However, nothing he did reasonably justified, in law or otherwise, being attacked and killed.”
The defendants had claimed they acted in “self defence” but the trial judge rejected the suggestion they were provoked in any way.
The 17-year-old boy was found guilty of murder and handed a life sentence with a minimum term of 15 years.
Kibble, from Bexley, south-east London, was found guilty of murder and jailed for life with a minimum term of 14 years and nine months.
The 15-year-old, who “lured” the victim towards his more heavily armed friends, was given a sentence of six years and eight months for manslaughter.
The defendants were also convicted of being in possession of offensive weapons which was reflected in their sentences.
Sentencing on Friday at the Old Bailey in London, Judge John Hillen said the motive “as incredible was it seems” was that they were annoyed at the victim’s “boorish behaviour on a bus”.
He said Mr Stoyanov had been described by his loved ones as “easy going, compassionate and always ready to help others”.
The judge said: “He is described by his mother as being full of life and dreams and energy to achieve them.
“He had a sparkling personality and infinite goodness in his spirit.
“He was the joy of his family and his untimely death has devastated them.”
