Hey Eshan,
I can understand your apprehensions.You are right about wayne state. I had got an admit form wayne state for my masters but did not choose it. Colorado is a good option if you are getting 100% funding with a monthly stipend.IISC ofcourse would be the best amongst the three. However,an international outlook always helps and an international PhD would add a lot of value to your resume in the future. So it boils down to colorado vs KAUST. In terms of international recognition, a degree from the US is generally weighed more in the US and Europe when compared to a degree from the middle east. The big plus as you said about KAUST is the lab facilities they have. If you are really convinced with the research topic(based on your discussions with the prof), go with KAUST. the other thing to consider is what are your options after a PhD. If you are looking for a postdoc, a PhD from either Colorado or KASUT doesnt count much. The only thing that counts is your research topic. But if you are looking for work in the US or Europe, a degree from Colorado/any other US Universities will have a higher weightage compared to KASUT. Hope this helps.
If you dont mind, can you tell me the fellowship KASUT offered? Is it 30000 USD a year? Have they offerd free housing/medical insurance too?