@PhillyKeith I'd go with the CW916x APs. We use 9166-MR, but they are a replacement for the MR56. The more direct replacement for the MR36 is the 9162 and the MR46 is the 9164. However like you, we found that the 9166 was a similar cost to the MR46 so it is a no-brainer to go for the 9166.
@Ryan_Miles and @rhbirkelund mention the fact that the 9166 supports WiFi 6E which is quite niche. However the default configuration sets the radios as 2.4 + 5 + 5GHz as opposed to 2.4 + 5 + 6Ghz, so you simply get a higher density of 5GHz clients. Do make sure you get the -MR model so you don't need to manage it separately.
Regarding the MX105, bear in mind that it will only sustain 3Gb/s of throughput with the Enterprise license feature set. If you want advanced features it drops to 1.5Gb/s. The MX250 is the next model up.
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