I try to avoid the NIV whenever possible because it crosses the border between a translation and an paraphrase too often for my tastes. The ESV seems to be growing in popularity as the translation of choice for conservative Reformed Protestants (as opposed to "conservative evangelicals") from what I hear.
Related threads:
Google Buys Out all Bible Versions, Offers E-Tablet
ESV-Kindle-Only Churches Growing Fast
Hows the New King James version?
I love the ESV. I especially love to hear it read by Max McClean at this site.
The ESV is published by Crossway Books, but they are kinda cheap in material and printing quality.
I bought one made by Oxford Bible and it is of extremely high quality.