Best speaker brands for transient response

Interesting that most the OP's description of transients relate more to midrange and high frequencies, not bass.

"The target effects I use to test transiency are the crash-to-ring transient of a cymbal, fingers going across guitar strings, snare drum tightness.."

Based on this, I suggest it is not a question of bass alignment  (sealed vs ported) but rather the mid and high frequency performance that will provide the desired effect. Certainly the room and speaker placement can introduce reflections that can cause smearing in this frequency range. 

An interesting characteristic of dipole speakers (Magnepan, some electrostatic, open baffle) is that they interact with the room differently. Yes you may need to absorb the rear radiationwith suitable room treatment, however they do not radiate to the sides or the ceiling. I find this can give a clarity to the mids and highs that is very appealing...and the lack of a box can provide a very natural and uncoloured bass. Worth exploring.

I have the Magnepan 1.7i and enjoy them...I think you would find they have a good transient response.

Transients are impulse responses in relation to steady state and it can be measured. Impulse response is to a specific input from base level. It is used to check time alinement. It is not related to distortion but most systems with good transient response are also low distortion. It comes down to good power to weight ratio of the drivers with pistonic motion.

When it comes to transducers, “transient response” is how close a driver can mimic the original signal. If given a theoretically perfect amplifier and speaker enclosure, any deviation from perfect transient response is indeed driver distortion. The more imperfect the response, the higher the distortion.

You are correct that lower mass diaphragms tend to have lower distortion, especially if they can resist bending modes within their implemented bandwidth.

Sometimes a driver can have good piston behavior but still cause a comb-filtering effect, which is another, typically less subjectively offensive distortion. Regardless, any deviation from perfection is a distortion.

The reason higher quality drivers sound quicker, subjectively, is because they are lower in distortion.

Ported, sealed, OB, panel…all such designs can sound slow/fast or dynamic/anemic depending on how well they are designed and the quality of their transducers. Unfortunately, most dealer-sold tower speakers under ≈$7K/pair (and stand-mounts under ≈$4K/pair) employ very mediocre transducers.

What is a transient response?  I have not heard of that term before.

This link gives a good overview to augment @helomech's explanation.

https://www.hifireport.com/understanding-transient-response-in-audio-a-beginners-guide/?utm_content=cmp-true

Interesting that most the OP's description of transients relate more to midrange and high frequencies, not bass.

Correct -- this is something I look for in mids and highs, also it also applies to what may be described as "fast bass" at the cost of bass extension.

This sounds about right:

Yes that’s it. Thank you for posting that.