Just by the T45 having a higher placed main radar, the Type 45 is superior to the 054B in engaging sea-skimming AShM (the most common threat to a ship right now). Aster is a lighter, smaller "dart", with bigger wings and PIF-PAF in comparison to HQ-16F which is a very big and heavy missile without a lot of control surfaces, this most likely means that Aster has a better p/k. There are a bunch of S-band GaN AESAs in Europe, but many of the warships carrying them are currently in the building process. Some examples are: NS100, Sea Fire, TRS-4D, Giraffe 4A, SPY-7.
If you honestly believe that then there's no point in having a discussion with you. The ships are meant for very different missions. Regarding overall capability (ASW, ASUW & AAW combined), I agree that Type 054B has an edge over T45 but the T45 is a specialist AAW as I've told you many times.
The HQ-16's cousin, the Buk, has popped everything from HIMARS rockets to AGM-88s. Plus it's about the weight and size of a Standard SM-2 missile, has similar wing configuration, that in fact the Soviets were accused of copying it. You also forget that given the missiles are VLS launched they would have thrust vectoring, which the HQ-16s have over the Buks which don't have thrust vectoring.
As for GaN, China makes and processes it to the point it globally dominates this industry. The compound is so freaking common it is commonly used in smartphone chargers. It is natural the Chinese would exploit the compound for various uses including radar, just as they did with rare earth elements and permanent magnets. Recently China has decided to ban exports of the stuff.
It maybe higher placed but not by much. The problem with SAMPSON is that it is an S-band radar and S-band doesn't do well with sea clutter near the surface level compared to higher frequency bands. That's why the Baseline 9 AEGIS adds an X-band SPQ-9C for surface level detection while the Chinese uses the C-band Type 364 radar on top of just about every ship. The 055 boasts a four set of X-band radars and the latest batch of 052D has rotating AESAs now on the top mast that boasts C/X band frequency.
Another point to be made is that SAMPSON is air cooled while the 052C used hybrid air and liquid cooling while the 052D uses liquid cooling. Even with all GaAS used, liquid cooling is a guarantor that the elements would have higher peak power that would necessitate such use of cooling.