I was trying to find a quick and easy way to combine or merge multiple TIFF images into one TIFF and found the searching to be quite annoying. Mostly found software for trialware overbloated garbage; then, I ran into something from AutoHotkey called FaxTool.
FaxTool is a small tool that will combine or split PDF and TIFF files. Quite a nice tool. I found it to work very well and maintain the image quality.
I did download another tool called “TIFF Merge Split Utility” but that didn’t keep the quality and color of the original files.
You can get FaxTool from here: http://www.autohotkey.com/community/viewtopic.php?t=46061
Screenshot: