I don't have Ultrafire C3 but I have Fenix L1D/L2D, Romisen N3, I3 and Akoray which all uses AA cell. From what I have read Romisen quality is better than Ultrafire in general. From my short experience the Fenixs are better than the budget one in most areas.
Firstly, the beam profile of Fenix is smoother, i.e. the transition from hot spot to spill is more gradual and the spill is brigther. Budget ones have more distinct hot spot and dimmer spill. Secondly, I think having no memory is better than having memory. Imaging switching off your light at the max brightness and switching on when it is pitch dark, it will blind you momentarily. Fenix implementation of always switching on to low mode is better.
Fenix is also know for its efficiency, hence its run time is longer than most other lights. My Akoray has only half the run time of L1D at the same brightness, although it may have something to do with its programmability. Lastly, Fenix build quality is also better and if I need a reliable light I will grab my Fenix instead of the budget ones. However, you might still find some uses for the budget ones e.g. putting in the car glove compartment, etc, so buy both!