Obviously, the better way to reach an impeachment is to investigate him for a decade old real estate deal and then charge him with perjury after he lies about an affair with a consenting adult.
Whitewater and Clinton's impeachment had nothing to do with each other. You can say Whitewater was a waste of time and money, just as Mueller's investigation was a waste of time and money, but there is no reasonable argument against Bill Clinton's impeachment. It didn't come about because of Whitewater.
Clinton was sued by Paula Jones for sexual harassment. He gave a sworn deposition in the case. In an attempt to establish pattern of behavior, Jones' lawyer asked him about an affair with Monica.(they'd been tipped off by Linda Tripp) Under oath, Clinton said he had never had sexual relations with Monica Lewinsky. Under oath, he lied. He also suggested to Monica that she lie. Physical evidence(including recorded conversations and the infamous dress) existed that the President of the United States had committed crimes. There was no guessing. He then admitted to it.
So faced with evidence of a crime, and then admission of a crime, what course of action should have been taken? The farce of it all is not that he was impeached, but that in the face of overwhelming evidence, no Democrats in the Senate voted to convict, making it impossible to reach the two thirds majority needed. The man admitted to the crime, so how could he have been found not guilty?
If that is the precedent to follow, then I see no way whatsoever that there is a real case against Trump. There was a rock solid case against Clinton, while Trump's case is circumstantial at best. The biggest difference is more people loved Clinton while more people loathe Trump. Not liking him is not justification for impeachment and removal from office. He won the election. If you want him out of office, beat him in the next election.