Use both, but don't overuse either.
Both techniques get dated. The more you see of each, the more you get used to which techniques were used and the easier it is to spot them. I was quite horrified at the bad CGI used in the 3rd Aliens movie when I watched it recently. It really detracted from the movie, IMHO, whereas the practical effects were better, if not actually good (Bishop, for example).
On the flipside of the coin, I feel that MOST of the effects used in the original Star Wars movies were excellent and don't detract from it at all. Some of the explosions could well be improved on, but not easily with 70's technology.
I prefer practical over CGI, but that's largely because I can spot CGI effects pretty easily and hate when they're done poorly.
Good CGI used sparingly and mixed with practical techniques can be very convincing. Jurassic Park is a good example, although the animation (movement of the CGI models) wasn't quite up to the quality of the rendering. It's still acceptable, whereas a lot of othe movies from the same time that used CGI have become dated more quickly.
TLDR: Use the right tool for the job, moderation is important.