As you can see by the above posts... it's subjective. Read the reviews of different GTX750Ti and analyse some key features such as:
Game performance
Noise (under load and idle)
Running temperatures
Form factor
Pick which features are most important to you and pick your card based on that, I personally don't care about the noise, but if you're using your PC as a media centre of some sort you'd want a card with a passive cooling system (or a very quiet fan...)