Both are equally good. Red fort is more of a fortress which you can walk through and be in awe of this architecture. Also now we have a metro station there India Gate is much better during sunsets, if you are in the right angle you will be amazed on how well you can capture the sunset :) Also you can relax at India gate in one of its parks and enjoy cool breeze now...
Well its on you both have their place..redfort enrich ur history plus ur knowledge towards good and bad side of kings where as india gate makes u proud and soul buildingblock of rocks make u feel joys and proud where u can feel and experience the sacrifice and history