Its always a matter of opinon. Its really not that important to me. If you do not like CFS3 graphics do not fly in it. I personaly like the different graphics and feeling that they give me. I believe in diversity and in having different experience. In my opinion they are both fine Sims.
You fly in the Sim that gives you the most satifying experience!

The reason I like CFS2 so much is that you can fly all the the World and in particular all over the Pacific some thing that most Sims cannot Offer. CFS3 does have a Pacific addon but its a bit limited in comparison. I"am a World war two Simmer and do not like to be limited to any one Theater.
But CFS3 is a fine Sim.
James007