Temple Run 2, Agent Dash and Pitfall for the behind the back view and Jetpack Joyride and Punch Quest for the side scrolling view. Temple Run 2 is the ome that seems to hook me the most.
Two awesome games that havent been mentioned: Gunslugs is an endless run and gun that has many ingredients to stay on every endless fan iDevice. Tilt to Live is from 2010 and its not a runner, but is an endless gem that never gets old and has plenty of fun and GameCenter multiplayer, and its free. Other endless games worth mentioning: PlicPlic bringed something new to the table and made me smile while playing it. Not many games can do that. Super Mole Escape has a coin gathering technique that gives you boots in order to advance, making you want to collect every single one without the feeling on grinding. Doodle Jump is old and its main game lacks modern stuff, but its multiplayer is addictive. Hundreds has an endless mode that very interesting and fresh, and has plenty of fun.