I enjoy both types, and regularly fly a Warrrior, but tend to agree. The PA38 has many atttributes that make it a good trainer,and the PA28 has many attributes that make it a good tourer.
You can happily train or tour on both, but I think that most people think of the PA38 as the better trainer - and once licensed you'll only need an hour or so in the PA28 Warrior / Archer / Dakota / etc. to be able to use that.
G