BBC One should be more ambitious and take "more creative risks in peak time", the BBC Trust has urged.
It also said BBC Two should make shows that were "clearly different" to those on One even if that meant less ratings.
In a review of the channels and BBC Four, the trust praised all three for high-quality programming.
BBC Vision director Jana Bennett said the findings endorsed "the strength and ambition" of BBC plans to deliver "even greater quality and originality".
In audience research carried out as part of the review, many respondents said BBC One acted as a benchmark for other broadcasters and praised its drama, news and natural history documentaries.
The BBC Trust's report said: "The channel needs, however, to harness its scale and size by being more ambitious and taking more creative risks in peak time, particularly by increasing the variety of programming in pre-watershed peak time and in showing greater creative ambition at 9pm."
It also said the "the clarity of BBC Two's role as a challenging and distinctive alternative to BBC One has diminished in the multi-channel world".
'Formulaic and derivative'
In interim findings published in July, the trust criticised BBC One and Two's daytime programming for "lacking quality" and being too similar.
Audiences told the trust that long-running antiques and property shows made viewing "too formulaic and derivative".
Shows under scrutiny included Cash In The Attic, Homes Under The Hammer and Bargain Hunt.
The trust has now praised daytime plans put into place by the BBC including cutting the amount of factual entertainment programming and a moratorium on commissioning new property or collectable shows.
The plans also include year-round slots for current affairs, social issues and consumer affairs shows, repeats of peak-time programmes on BBC Two in the early afternoons and more original drama.
The trust praised BBC Four for its strong reputation in arts and culture and its efforts to make good use of archive material.
But the main challenge for the channel - which the trust said was watched by about 9% of the UK population - was "to increase its impact".
This could be helped by "more effective sign-posting and promotion from other BBC output", the trust said.
Ms Bennett said audiences had a strong appetite for "fresh and new ideas" on TV and that the BBC would take a leading role in feeding that.
Audience research showed that BBC channels led other broadcasters for "quality, originality and distinctiveness", she said.
"Shows currently on-air like Strictly Come Dancing, The Trip, Getting On and Wallace and Gromit's World of Invention demonstrate this in practice."
She added: "On BBC One, we will seek to bring even greater range and variety into peak, building on a very strong base - programmes like Sherlock, Bang Goes the Theory, Five Daughters and Outnumbered, to name but a few. "
She said BBC One would provide more range and variety during peak viewing, building on programmes like Sherlock and Bang Goes the Theory.
She said the corporation would ensure that BBC Two was a "highly distinctive alternative to BBC One" with programmes like Wonders of the Solar System and The Normans.
And BBC Four would "seek to achieve even greater impact and credit for high quality, highly original pieces", Ms Bennett said.