The answer is simple. Visit any health or wellness area and bear witness to the most USED equipment there. Treadmills, elipticals, and recumbant bikes! I know these aren’t the most beneficial machines for training but, the are the ones that people use MOST on their own. That makes them the most beneficial investment. After that, keep it uncluttered and beige. Not the color but the feeling; like a day at an uncrowded beach. That way when it is packed, it won’t feel as cramped.