Sam Wilson is the only choice as the next Captain America, for so many reasons. Primarily, he is a sign of change and growth in America, and should be represented in the MCU. Bucky is just a glorified Punisher--he never hesitates to brutally murder anyone, or blow up as many buildings as possible. Yes he's an intense spy and skilled fighter, but that's it. He's just an assassin, and as much as he tries to redeem himself for his past, he still just acts as a violent trigger-happy soldier. Sam Wilson (from the films) is a veteran, just like Steve and Bucky, but clearly he channels his past in healthy and productive ways. In "The Winter Soldier" he helps run a support group for soldiers with PTSD. He is a soldier but his first mission is to heal and help others. Steve and Bucky were raised and trained in a World War, where they were trained to fight and break the enemy. The world is different, the world doesn't need stormtroopers, they need peacekeepers and healers. As Captain America, Sam Wilson can do all that and more. He can fight the good fight while always keeping combat as the last resort. Sam Wilson is the only choice for Captain America.