Obviously there’s no one best frame, everyone wants different things from their bikes, we’re all different shapes and sizes and styles and we do different things with them, and even when we’re doing the same thing we do it different, and even if we do the same thing the same way we don’t want the same things from the bikes we do it on.
So I’ll recommend a Soul, because I’m a fanboy. But there’s loads of good steel frames, I just found the Soul was a perfect match for me, there’s probably others which i’d feel teh same about and obvious there’s others that feel the same about 20 other frames.
Otherwise, it’s hard to argue with a 456, they’re versatile and inexpensive.