Make the Marinade. Whisk together the olive oil, lime juice, lime zest, garlic, honey, soy sauce, chili powder, chipotle powder (if using), smoked paprika, cumin, brown sugar (if using), salt, pepper, and jalapeño in a large bowl.
Prep the Chicken. If using chicken breasts, pound them to an even thickness (about ¾ inch) using a meat mallet or the bottom of a heavy pan. This helps them cook evenly on the grill.
Marinate the Chicken. Add the chicken to the marinade and toss to coat well. Cover and refrigerate for at least 30 minutes, though 2-4 hours is ideal for deeper flavor. Avoid marinating longer than 8 hours, as the lime juice can affect the texture.
Preheat the Grill. Heat grill to medium-high heat (400-450°F). Lightly oil the grates to prevent sticking.
Grill the Chicken. Remove from marinade and let excess drip off. Grill over medium-high heat until cooked through, about 5-7 minutes per side for chicken breasts or 6-8 minutes per side for chicken thighs, until the internal temperature reaches 165°F.
Rest and Serve. Let the chicken rest for 5 minutes before slicing. Finish with a squeeze of fresh lime, a sprinkle of chopped cilantro, and a pinch of Tajin if you like. Serve with lime wedges.