I own both and I love both. I have a female GTP who looks like a Sorong type, but not sure of her lineage. She is handleable, but not in the evening or when she smells food. She's perpetually hungry..lol. I also have a male Biak GTP who is the biggest sweetie. He's docile no matter what time of day or night you attempt to pick him up. When he arrived he had an oral abscess from swallowing a tooth, so his first experiences with me were me sticking him with antibiotics and soaking him every night...and he still doesnt' bite...lol.
My Esmeralda is the calmest of my arboreals though. I know you'll probably never hear anyone else say this, but I trust her more than I trust my ball pythons. She's never startled, hissed, or shown any sign of aggression to anyone, and everyone who sees her wants to hold her, pet her, and fawn all over her. And she just seems to eat it all up..lol. She eats well, sheds well, has been healthy since I got her (knock on wood), and is stunning.
I honestly think you can't go wrong either way. ETBs are less common, but you can find hand tame ones if you look hard enough. Hand tame GTPs tend to be more common, and they tend to be a bit hardier.
I like both of their appearances. Honestly before I got any of them I preferred the GTP face. I really wanted a GTP but found Esme on Fauna and got her instead. A few months later I got Mystique, my female GTP. I got Archimedes, the male, in September. Mystique is not the prettiest GTP by far- she has quite a small head and a rather pointy nose. But she has nice blue accents and the blue line down her back and yellow eyes with red crosshairs. She's a neat girl and a good snake. Archimedes is absolutely amazing- he has deep golden eyes that look like they go on forever, and a tall nose with huge nostrils and heat pits. He's gorgeous!
Honestly, I think if you were able to interact with an emerald and really get a look at its face, you'd like them just as much. It's a whole different look, but just as cool in its own right. Esmeralda also has golden eyes, very metallic, and the lips full of heat pits is really cool- she looks so fierce and primal, but she's such a doll. She's my pride and joy- my little gem.
So I guess in conclusion, I couldn't say which one I like better. Get one of each!