Broadly speaking, think of the port as giving you a bigger "budget" of low frequency response for a given driver and box, assuming that you've chosen a driver that works in a ported box. What you do with that budget depends on how you want to play other typical tradeoffs, such as low end extension versus overall sensitivity.
Here's a brief article on a ported design, where I was aiming for a response curve similar to a particular classic sealed cab, but with considerably higher sensitivity and power handling: http://personalpages.tds.net/~fdeck/bass/smallbox.pdf
The article compares two idealized designs, both with the same driver, at opposite ends of the tradeoff spectrum.
As for your listening experience, you have to watch out, because sealed-vs-ported probably wasn't the only variable in play when you compared speakers.