Every example I hear of the Slate, the top end “air”, just doesn’t sound right/exist. I hate using cliche terms, but it doesn’t sound open. High mids are weird. I wanted to love it, especially with the $499 deals on it right now.

Regardless, I just ordered the Townsend

so, basically i need two microphone ppreamps, gain matched to use this mic?

Yes, that is correct. But you can the Calibration switch on the Sphere L22 to gain match the channels if they aren't perfectly matched.

I only own the slate and I have only used it once or twice, I really wanted to love it but I just never wanted to come back to it over my other mics.

To me it always sounds better without any of the emus on (but very vanilla) - could definitely make it work if it was my only mic, just doesn't get me excited.

Haven't tried the Sphere but am pretty interested in it, a few of my friends who I trust use it almost exclusively.

I only own the slate and I have only used it once or twice, I really wanted to love it but I just never wanted to come back to it over my other mics.

To me it always sounds better without any of the emus on (but very vanilla) - could definitely make it work if it was my only mic, just doesn't get me excited.

Haven't tried the Sphere but am pretty interested in it, a few of my friends who I trust use it almost exclusively.

You can technically use any of the preamps on their approved list.
But, considering the mic comes with a voucher for the UAD Sphere plugin, it seems like an Apollo is the way to go.

(This is the list of approved preamps and interfaces)
https://townsendlabs.com/prelist/

Matching the gain of both should be pretty easy on most interfaces, though a little more challenging on raw preamps. (Most interfaces have a way to "link" 1/2, 3/4, etc.)

It's a breeze on the Apollo interfaces though, and the cool thing is being able to monitor your mics live, without latency. It's nuts to be able to hear an accurate model of a Neumann U87, running through an accurate LA-2A, and into an accurate Pultec EQP1A.. all live. I really feel like the two companies, put together, really knocked it out of the park.