It was a tough decision for me back in 2010 but I went for gli 2010 because of the following reasons.
Gli is brand new , X is used one
Gli got warranty , X got none
Gli follows a periodic maintenance schedule at the 3s dealerships with readily aval spares which is easy for a person like me with busy routine whereas for X you ll have to workout a maint plan and source out the spare parts either from kabar market or other shops
X spares are bit expensive
Finally new car is a virgin one and X being a 2nd hand used one . Both carry almost same price tag rather X is higher sometimes so dont worth it. had the X been on the lower side pricewise then it was ok