I thought my Logitech sub was good... until I bought my Polk sub. I thought my Polk sub was good... until I bought my REL sub. Now I just think my REL sub is good, we'll see what the future brings.
I think the most important thing here is that you take pride in what you have, I admire that. My first car had 15 year old peeling paint, but I still waxed that sumbich once a week. Take pride in what you have, then when you get something better, you'll appreciate it that much more.