Hi! Welcome to New York! Unfortunately I haven’t found a good sub that fills that chicken tender void in my heart, but I have found a few places that do regular subs (like ham, turkey, whatever) REALLY well. But one of my favorite places to get a sandwich is City Subs in Park Slope. It’s closed right now for renovations, but the subs are AMAZING and you should definitely go when it reopens. I also really like Bierkraft (also in Park slope) because the sandwiches are great and you can get a huge growler of beer to go with it for around 10 bucks.
And if you’re looking for good fried chicken, just not on a sandwich :( , head to Sweet Chick. It’s the best chicken and waffles I’ve ever had in my life.