Hi, aSem-1
HF100 or D90 is depend on your main purpose.If your mainly purpose is for taking good video quality that HF100 is your choice.Video quality from D90 is good but not great and can not reach HF100.
http://www.amazon.com/gp/product/B00...SIN=B00114162K
but if your mainly for taking picture Nikon D90 is the way to go 12.3MP is great for taking picture.
http://www.amazon.com/gp/product/B00...SIN=B001ENOZY4