I personally like both the Terracotta Warriors and the Insects, and would be very happy with either.
Initial thoughts/caveats on both:
Terracotta - Very nice to do an Asian flavored army, to complement to African flavored Umenzi and show that Battleground is a worldwide thing. I like the general idea of terracotta warriors a lot, too--it has just enough tie in with history to give it a very nice flavor--inspired by something other than Dungeons & Dragons.
I put a few comments last years on the army thread http://yourmovegames.com/forum/index.php/topic,1340.0.html
which still hold. The biggest one is that skill 4 sucks, and at that skill this army will still be a speed bump for elves, neutralizing what was supposed to be the reason to do a high-toughness army. Of course, in that thread I suggest some things that cold be done.
Insects - These could be great fun! I mean, who doesn't like to kill insects--no scatching your head saying "Couldn't the High Elves & Ravenwood worked out their differences peacefully?" Also no guilt when your error gets your bug army slaughtered--just hatch more next week.
(I used to feel terribly guilty every time one of my High Elf units perished.)
One thing which is both a great potential, and a potential huge pitfall, is that an insect army could go SO many different ways, many of them very wacky. Do you have special rules for queen bugs, poison, web, hopping, phermones, bravery, metamorphosis, etc. or not? I can already see lots of people each pulling the faction in many
different directions--so whoever is in charge would need to keep a very
firm, steady hand on the process.
In short, both armies could be really cool. Doing an insect army is riskier, definitely in terms of downside, possibly (I'm really not sure.) in terms of upside.
I supposed, if I had to rank them, it would be Terra Cotta #1, insects #2.