On-board I carry the Gerber Para-frame II. Folding high carbon Stainless blade w/stainless handle. Clip point blade (serrated). Clip on handle allow it to be clipped onto edge of pocket so it is easy to get at when needed. Very sharp and holds an edge well. Not very expensive (around $25) so if I should loose / break it (drop over board) I won't feel guilty havig to buy a new one.
When not on board I carry the Para-frame mini. ($10) This is my third or forth as I alway forget not to take it with me to the airport.