Well like i mentioned b4, despite the (deserved) acclaim and contributions to the titans mythos, NTT has not aged well. If you can stomach overly verbose, borderline campy story telling, then by all means go for it. Perez is fire on art duties tho.
Annihilation i feel gets a lot if praise because it dusted off a lot of characters that were sorely neglected for years, and threw them into a space war of epic proportions. On premise alone it's cool, but imo the story is just alright, and despite the awesome covers, the interior art gets bad at times. But it does lead into the rest of what becomes the DnA saga, so it has significance there.
Anyways, to the question. I'd pick Annihilation based in my bias for modern writing and in turn its re-readability. But neither are stellar. Anything else you might be interested in? I feel like i want to recommend something that's good lol
Edit: if you want some decent titans stuff, Young Justice and Johns' TTs are currently getting released in chunky trades. Fair warning, Johns work is heavily marred in event related stuff throughout, but still manages to have its moments