A patio is more permanent and solid.

I think it depends on the land.
If the yard is flat and only a few steps down from house a patio is nice, but unless yard is one step out the door, then you need something for a transition to the deck (steps).

If the main level of house is a full flight above the yard, then a deck might be better choice

My home is three steps down to yard, so we added a small deck off family room which leads us down to the patio. So we have both, but the patio is what we use for lounging and dining, the deck as mentioned is just to transition is down to patio.

I find a patio easier to maintain. A deck requires routine staining and waterproofing. They eventually rot. Termites can be an issue. I still like a deck, but just mentioning things that should be considered. A concrete or stamped concrete patio pretty much just needs a power washing now and then. A paver patio is nice but they are on the high end for cost. If you were to do concrete, I would have them add stain to the mix, as regular concrete can look dingy after awhile and stains with leaves and debris.

Pavers last longer as others have said. If you want some ideas on styles, one of my imaging clients, Go Pavers, has a useful way to look at styles and compare costs to what is available in your area:
http://www.gopavers.com/pavers-collection/

Not sure of your climate/$budget but I would strongly steer you towards a screened in porch! We added first a deck and then instead of extending deck for more seating we added a brick paver patio. Both great spaces but I would trade both for a single screened in porch. Just another thought for you to consider...