We have used many over the years. Not going to say what is best...
For a traditional butterfly style, we like Jenvey. Used them countless times with great results every time. We have also used PMO, Clewett, TWM (borla now?) Hargett (did some testing for them and not even sure if they are around?) and RHD.
Our go to is the Jenvey, high quality, easy to adjust and maintain their adjustment. We adapt the throttle set up a little to our liking. On same engines, they made more power than the PMO's but the PMO looks like a weber.
Jenvey also offers their heritage line, which looks amazing if you want a carb look, as injectors are hidden. We have not tested those. The Clewetts are very functional, everything is well thought out mechanically, just aestetically, they are a little "cludgy".
Was not impressed with the RHD at all. Too many pieces involved (I get it, modular to fit many applications) the linkage seems a little "light" for the appplication and they had a complete lack of instructions/tips with the kit. Client really wanted them, so we got a set.... They perofrmed well, but just not quite what we were looking for.
Not tried the AT Power ones, may some day soon. The clients we have built motor for with the all of the listed ITB's have been thrilled with the performance, driveability and throttle response. So we are happy.
Your ECU choice and tuner choice are likely more important to get good performance and driveability.
Cheers