Frolic...was the 1st Death Angel I purchased, so I tend to reach for that one first. A little more controlled thrash compared to their first release, The Ultra-Violence, but still a great album. Act III is good as well, with a little more diversity in the songs. You really can't go wrong with either.After a few years off, they came back with another killer album, The Art of Dying.
What I'm trying to say is get all of Death Angel's releases. They're all good. You won't be disappointed.