The proper choice between these two alternatives is very
much a function of the traveller's interests. Orlando is
terrific if you're partial to Disney-fied artificial
realities, and all the tourist-y stuff (chain restaurants,
etc.) that builds up around same. Disney does a superb job
of this sort of thing, and attracts astonishing crowds (and
$$$) year-round by doing so. If this type of "entertainment"
leaves you cold, however, so will Orlando. Tampa is much
more "real", and a gateway city to a lot of lovely beaches
and "typical Florida" landscapes and byways. And if you like
adventure/theme parks, Busch Gardens is not to be missed, as
someone has already suggested.