Nanogy 95 or Nanogy 98. 95 is more durable and much cheaper but 98 is more powerful and still very durable. Bare in mind that both Nanogy strings don't offer much feel.
If you want to take a step Down, BG80 provides power as well, but with less compromised feels and less durability. Nanogy is your best bet though, as said by Danstevens.
i think the best durable+powerful string i've come across are BG-85, but then again i've only used BG-66,BG-65, nanology 95 and of course the wonderful BG-85
Are the nanogy strings better at higher tensions? For example, I'm using BG 80 @ 23 lbs right now and I want to switch to NBG 98. Should I increase the tension or keep it at 23 lbs to keep the same effect?
that's a personal preference. keep it at the same tension, though, to preserve your joints and what not, and take it up after it pops once.
Keep it at 23Lbs. Maybe experiment a bit next time. Also, you may want to try NBG-95 first, it's cheaper and feels similar. If you like the muted feel, then move on to NBG-98.