Depends on what you plan on doing with the picts when you are done. If you just want some cool picts to hand around easily.. go for the lowest price you can. Hand them out like Doritos. Munch all you want, we'll make more.
If you are planning on archiving them, then you will need to invest in a proper HP, Canon, or Epson printer using their archival grade inks (pH neutral) and archival grade paper (acid free). Then you then need to store them in an archival fashion. Black plastic archival envelope in a (more or less) temperature and humidity controlled environment. Under your socks in your drawer is actually a good place.
The on-line services are primarily geared towards low cost and quick turnaround. Some of them do have archival grade services (you need to check!). But, if you really want to make sure, do your research an do them yourself.
As for those that think digital is the way to go... yes and no. If you really, really, want to make sure it will still be there paper is still the only medium that has the longevity track record. Properly stored, centuries to millennium (or more) are not uncommon. Dead Sea Scrolls anyone?