What is the best and easiest to use for onsite inspection reports for a tablet?
I like Report Host “cheap and easy” In my OPINION.But I am not sure about best. Dom’s customerservice is hard to beat with HIP Home inspector pro. I do not know about home gauge
How many bells & whistles do you want?
If you want many choose 3D. If not go with a less expensive program.
Most programs out there are good but some have more options than others.
It’s all about you & what you want.
Incidentally, 3D used to have piss poor customer service, thay have done a 180 in that department & now is IMO have among the best support in the industry.
For me this is what matters the most.
Colorful and sure is long 
check out these samples. I really like their style and you can customize them somewhat. http://www.reporthost.com/samples.asp
If you use a tablet on site report host is the way to go, you download the report once , work off line and upload at the end of the inspection, drop in the photos, boom done!
I just started using the tablet software 2- months ago and like it.
I agree with the above statements!
What type of tablet are you referring to ? It all depends upon the tablets Operating System. If you are talking one of the new Surface Pro 3 devices you want an app that will use the built-in functions of the device and be geared towards navigating easily with your finger and gathering data quickly with very large text and buttons. If the app is geared towards creating a report and has a lot of data on the screen it will be very frustrating trying to use in the field.