Depends on what you watch. LCD is best for day-to-day TV (clear, sharp pics). Plasma better for closing the curtains and watching the blockbusters (better blacks) and sports.
Also read somewhere that both have about the same life span, but LCD's don't suffer burn-in
T3 mag awarded the JVC LT-32DX7 best LCD TV £1400, and Panasonic TH-42PX60 best Plasma £2000.