Factory default one is just fine for me, I used to use Twitterrific because they had better blocking but now I think the factory Twitter took care of that
Tweetbot. I occasionally go back to Twitteriffic and even more rarely back to the official Twitter app. The official app lacks mainly in the image viewing department. Tweetbot and Twitteriffic allow me to see images in line and open then and scroll out just as fast without missing a beat. The official app require clicking on the link and then going back. Too much hassle.