Video recorders are the most crucial piece of equipment you can have at an investigation. This isn’t to say that the VR is the best at capturing and documenting activity, but it provides the most blatant of evidence when found. EVPs can’t be proven to be real, EMF findings carry little weight until entities are actually proven to be causing the fluctuations, and thermal variations don’t prove much of anything to the skeptic other than thermal variations.
With activity on video, it is hard to dispute a finding. If it is authentic footage, you can take it to a video professional for analysis. If he says it’s authentic, that may be all the confirmation you need. If he says it’s fake or is a false positive, have him explain why he thinks that and how he would have created that effect, then you can create that situation yourself. Once you’ve created the situation, if it causes the same effect that you videotaped in the first place, perhaps you got a false positive. If the effect wasn’t recreated, relay that information to the video professional and try to get another explanation and do this until there is no other possible answer for that activity. Once that is accomplished, take your findings (to include everything you went through with the first video professional) to another one. Do so until you have exhausted your resources. Once this has been finished, your findings can be presented to the general public as you wish, and who could dispute it? There is a figure of a man, and there is no logical explanation for its existence.
This being the case, I believe you can effectively investigate with only a VR, though 2 might be a better idea in case something happens to the first (I have had many full batteries suddenly drain, that is good documentation to capture). EMF meters, thermometers, EVPs, they are all great to present to a client to solidify their beliefs that their place is haunted (very rarely will you investigate a property that isn’t already believed to be haunted), but as far as proving that paranormal activity is real is a different story.
One of my own main goals for investigating is to prove to people that these things exist, therefore the less absolute the evidence, the less I need it. In the course of documenting activity to determine if an area is housing some sort of activity I may turn to these other devices prior to recording video and taking pictures, but once activity has been established these tools get put away. It is always important to research the way you desire to research, rather than going through the motions that someone else told you that you should. Just because TAPS does it, doesn’t mean you have to. If everybody does the same thing all the time, how are we supposed to advance?
Keep an open mind, remain objective, and go after it!