There's already a t3 vs nova thread.
I've been using both for a few days with the same juice and different ohm and volts for each. One has to decide if the pros/cons of each outweigh the other's.
Pros of vivi unmodified:
-slightly better hit and taste
-Can change tip
-cheaper premade replacement coils
Cons of vivi unmodified:
-threads easily strip. Can change to a metal tank (almost the cost of another nova) with solid threads, but stainless steel still leaches chemicals. a glass tank enclosed in metal (for drop protection, not that I generally drop things) with a level window would be great.
-needs shaking to avoid dry hits
Pros of T3 (i'm using an MT3, same as T3 but holds more and enclosed in metal with juice windows) unmodified:
solid build, metal threads
don't have to shake to avoid dry hits as long as not vaping faster than juice can flow
Cons of T3 unmodified:
-can't change tip to rubber I prefer
-I think the vivi tastes better
This might help to get better tasting hits and no dry ones from the T3 though:
cut away some of the rubber stopper on the shaft near the wicks to allow the wicks to absorb more. If you just raise it up the shaft, it will go back to where it was when the two interlocking air shafts screw together, which also might cause the rubber stopper to clamp on the wicks and reduce juice flow. Not fully tightening the two parts together might not cause the rubber stopper to clamp on the wicks also.
I removed the two wicks besides the coil wick and it didn't flood, but I couldn't tell a difference in taste.
I want to remove the 2 extra wicks besides the coil wick AND all/most of the coil wick and use the uncut rubber stopper near the wicks to find if there's a sweet spot that allows just enough juice in to give a drip-like hit without it flooding or not pulling at all because the vacuum effect is lost. It might flood to the battery though. I'll eventually try it in hopes to not waste a coil. If it works, T3 would have a better hit than the nova, it doesn't have to be shaken, and the T3's built better so then the T3's better in all categories except pre-made replacement coil price and can't change the tip.
FWIW, though, I'm moving past clearos and learning about MODs; can get glass tanks enclosed in metal with juice window, SS wick tastier and healthier, etc, just larger in diamater.
Edit: I just tried removing all the T3 wicks and leaving the bare coil. It didn't work. It leaked into the battery and the juice doesn't even reach the coil without wicks. I had to shake it before hitting to get juice to the coil, but once that's burned, noting else flows and I barly got a hit.
Removing the two extra flavor wicks and leaving just the coil wick helps though.
So I say the Vivi nova gives a slightly better tasting hit and is cheaper for coils, but is built worse and needs shaking.
I changed out the vivi tip to a tiny CE2 rubber one, which compared to the stock tip gives a better flavor because it's closer to the coil and I think I can actually taste the stock plastic tip.
final edit: thinking the nova tastes better might be because I have to give the T3 half a second to fill the air duct with vapor, otherwise the first impression is airness. In conclusion, I think the nova tastes better/more liek dripping, but not by much.