I have multiple straighteners (original old-school Chi, Sultra Seductress, Conair Nano Tourmaline, Hot Tools, GHD Platinum, a Titanium one). I have extremely coarse, thick, naturally wavy hair. My favorite is the GHD Platinum. Heats up super quick, does a great job in one pass. No frizz, no weird "bendy" spots or underlying wave. I never have to do a second pass, and it really locks in my straightness & lasts for 2-3 days if I skip washing.
My second choice would be the original Chi - it is a very, very close second to the GHD. However, mine is 10+ years old, and I've heard they are different quality now. My stylist uses a Croc on me, and it works well.