Though I've only been vaping for one week, my son gave me a flat tip that fit my 510 and I really liked it. Must say that it did knock the wick off my atomizer before I noticed the inside was shaped different than the 510 carts. Just pushed the wick back where if came from and it still works fine. Just have to be more careful in the future, but my vote is for the flat tip.
my flat tips.