A small home gym will limit the number of different exercises you can do, so you could get bored but it's perfect for the person that just wants to keep in shape and maybe loose some weight.
The bigger the home gym, the more you can do .... more exercises, more ways to isolate the muscles you want to work on if you're toning up or building strength, and it's less likely you will get bored.
Any Home Gym Equipment will give you a good workout, you need to decide how serious a workout you want ? There is no point in getting a bench and some weights, when you know deep down a better home gym would motivate you to do a workout every day.
So when it comes to Home Gym Equipment