First, let me just say that you can tell the bias by the choices given to us....but on to the larger issue. There are problems with the accusation.
For starters, the desire to remove the prosecutor, Shokin, was already a policy goal of the Obama administration and of other western leaders due to the widespread knowledge of Shokin's corruption.
Biden DID make a threat...but at the time it was made, no one is even sure that the company his son was working for was even under investigation. And, as PolitiFact points out; no one knows if the company the son worked would even have benefited from Shokin's removal. The threat had to do more with enacting Obama's policy. Biden:
"I remember going over (to Ukraine), convincing our team … that we should be providing for loan guarantees. … And I was supposed to announce that there was another billion-dollar loan guarantee. And I had gotten a commitment from (then Ukrainian President Petro Poroshenko) and from (then-Prime Minister Arseniy) Yatsenyuk that they would take action against the state prosecutor (Shokin). And they didn’t. ...
"They were walking out to a press conference. I said, nah, ... we’re not going to give you the billion dollars. They said, ‘You have no authority. You’re not the president.’ … I said, call him. I said, I’m telling you, you’re not getting the billion dollars. I said, you’re not getting the billion. ... I looked at them and said, ‘I’m leaving in six hours. If the prosecutor is not fired, you’re not getting the money.’ Well, son of a bitch. He got fired. And they put in place someone who was solid at the time."
And, as a result, the Ukraine Parliment had a no-confidence vote and ousted Shokin.
If you want to investigate this...again...then let me tell you now that it will take a back-burner to Trump. Why? Well, the differences in each case. Biden can say that he was pursuing administration and EU policy as it WAS policy. Biden's actions had nothing to do with digging up dirt or asking a foreign national to help defeat a GOP contender to the presidency. Biden did not ask a foreign government for help in defeating a rival who was in his way to the White House. Trump did that.
Not only that but Trump is president and Biden hasn't even won the DNC nomination yet. Who holds the bigger threat to the US? Answer Trump does. Not Biden.
Look, like some of the candidate, I'm not fond of Biden. I don't think he should be president. But this accusation is already old and resolved news. Even if there were something to it, the allegations against Trump are far more serious and need to be addressed first.