IPV3 at 150 watts or SMY 260 at 260 watts, I own both and each have their strong points and weak points but both do what I need them for and that's firing sub-ohm
tanks at 20 to 30 watts.
In my personal experience, it's more a personal choice than one being better than the other. What are you wanting to do with it? What is your goal, getting maximum watts or long battery life or "mines bigger than yours"?
You can spend between $100 and $200 and get a good
mod or drop several hundred and get something like a Variant which will go to 260 watts just like the SMY 260 (Even the clone is $169.00)
Why do I have big VW mods, well I have a big ego and like to have big toys to match. There's absolutely no reason what so ever for me to own anything over 50 watts however I now own 3 that do 100+ and not a single one of them has been over 40.
So it's a personal choice, each one will have just as many people praising it as being "the best on the market" as there are pointing out every single little flaw in them. I own an IPV3 that someone returned to the shop because it was "the biggest POS he had ever owned" and it's worked absolutely perfectly in my opinion since I walked out with it. The store got a credit from the supplier, I got a new (to me) mod, they made money, the customer got something different and we are all happy.