Queen Elizabeth I I can chose another royal familyline to assume kingdom of Uk...Knowing her line is unfit,Who would you chose?

I'd choose me

No she can't. What qualifies a monarch of the UK is descent from the Electress of Hanover, which all those currently in the succession can demonstrate. It has no bearing on who they marry.

The Queen may abdicate (highly unlikely); what she cannot do is name her successor.

And why is her line "unfit?"

https://en.wikipedia.org/wiki/Internet_troll

She cannot choose who comes after her, it requires an act of parliament and agreement of all the other commonwealth countries to change the order of succession, she has no say as she will be dead! the order is charles, then william,then george, then his eldest child and so on as long as we want a monarchy.

NO. The Queen CAN NOT choose her successor. This is an act of PARLIAMENT. The Queen's line is NOT unfit. Parliament would have already acted if they wanted new successors to the throne.

my family line should be chosen, because most of them are already serving time at her majesties pleasure. ideal candidates.

If Queen Elizabeth 2nd's lineage is unfit to be the royal monarch of the UK then the British govt and its laws are unfit to govern the people of that country.

You can't discredit the Queen without discrediting the govt and the whole westminster system.

Do you see how nonsensical your question becomes ?

Obviously it would have to stay in her line so would be Prince William