I've read all three. Call of Cthulhu is the simplest and most player-friendly by far. Rules are easy and realistic. There is a LOT of material out there for it. It's the only game I'd play.
D20 Cthulhu is a gorgeous book but its basically 1920s D&D with Cthulhu. Not my cup of tea.
Trail of Cthulhu takes the tactics and applies them to your skills. You have to pick and choose when to use your skills (or at least the bonus dice for your skills) in each adventure. Not realistic (hey, I'm good at something in the morning but suck at it in the afternoon?). You don't even have attributes - only skills. How strong is your character? Who knows?
My opinion is to stick to the basics. Go for Call of Cthulhu.