Both Trump supporters and haters are pretty set in their stance with regard to the Russia investigation, so it's not worth it to type out a prolonged argument here.
What I find troubling is that many people aren't concerned with the unwarranted attacks on Mueller and his team, much of it coming from members of the House Intel Committee who are supposed to be running an objective investigation. There has been some very shady activity, especially from Devin Nunes. Just because McCabe and Strzok have political viewpoints (like everyone else in the FBI) does not mean that the investigation is automatically compromised. There's zero evidence that it is a partisan "witch hunt", while on the other hand the events that have unfolded thus far show that Trump, Trump's family, and key members of his team have ALL lied about having connections to Russian officials.
Even if the investigation shows no collusion between Trump himself and Russia, that's fine. What matters is that we get to the bottom of what happened so that future Russian (or other foreign govts) efforts are thwarted. I don't care who it is - if it's Trump, Sanders, Clinton - if there was the same cloud of suspicion that enveloped one of these politicians' campaign, I'd want it investigated. It's amazing how Trump supports cry foul about this investigation, but if it were Clinton the calls for her head would be endless. If Trump is innocent then there's nothing to worry about. Let Mueller carry out his investigation without interference. The way that he and the Republicans are acting only heightens suspicion in the public eye.