Heat oil in heavy Dutch oven over medium-high heat. Add both bell peppers and garlic. Sauté until peppers begin to soften, about 4 minutes. Mix in peperoncini and basil, then tomatoes. Simmer until sauce reduces slightly, breaking up tomatoes with back of spoon, about 5 minutes. Add pasta and toss until sauce coats pasta. Add feta and toss mixture to blend.