just give him some ergo clear. I know people say they like clicky. but they haven't tried it for 3 weeks straight. it gets on your nerves
If he likes clickies, why ergo clear? If you want clickies, you usually want some sharp and crisp tactility and/or some noise. MX will not do that. I haven't used any MX tactiles for 3 weeks straight, but I have used halo trues that long, since they came in my Drop ALT. The more I used them, the more I disliked the MX-specific tactile event and plasticky feel and sound. I didn't want to type on them anymore and don't plan to again. Topre and Matias tactiles though I keep in occasional rotation. I'm using 55g Topre right now, at another location I have had Matias quiet clicks set up for the last few weeks. I like those a lot more than any MX or clone tactile I have tried and I still don't like them nearly as much as a good clicky switch.
I'm good with noise. Especially a really bassy sound. As an example, when I listen to any modern rock music, the part that I enjoy the most is always the deep boom boom of the bass and percussion. I don't know what it is, but it just has a weird effect on me. I tried clickies and tactiles with a POM plate, and they both sounded amazing. I didn't like the feel of the pale blues however, and I absolutely loved the royals. Now I want to find an XXXXXXXXXXXXXXXXtremly tactile switch thats med-high weight. That's all. Oh, and also clicky.
If you want a thunderously bassy clicky switch, you want Alps SKCM blue. Unfortunately, they haven't been manufactured since 1989. They also fit your other parameters, and are considered by many to be the best clicky switch ever made (there is debate of course, but all contenders are vintage switches from the 70s and 80s). Alps SKCM white replaced blue and the early ones feel very similar, but they were produced for a number of years and underwent iterative changes throughout that time. Any complicated (SKCM) clicky Alps switch would still be hard to beat by anything manufactured today. If you want something modern that fits all of those parameters, you want box jades. I think their vague similarities to Alps SKCM are part of why they're so popular.
If pitch is less important, beamspring and capacitive buckling spring are also contenders for the best clicky switches ever made in terms of feel, for which you will find no modern analogues for comparison. Unicomp's Model Ms would be the closest thing without getting a new production Model F from Ellipse.
Bassy clicky switches are anomalous, very few designs have ever turned out that way.
A comprehensive switch tester (especially with as many of the clicky variants of the box family you can find) will help you to narrow down your tastes in clicky switches without having to hunt down expensive relics.