For $270 I would get the more advanced display, increased performance, and more ports
I think it comes down to:
1. Do you really need the extra performance all the time?
2. Will you notice the screen difference for SDR contents when you're not in a pitch black room?
3. Will you be able to use the extra ports regularly enough that it warrants not also just bringing along a dongle of some sort?
For me, it's easily 15" over the 14" Pro now because:
1. 15" Air is still faster than most if not all Intel MacBook Pros. It should already be overkill for most people. It's weird to me that suddenly it's "not enough" for anyone. Sure, the UI of my app builds in 74 seconds on the 14" versus 143 seconds on the 15". I'm not going to die waiting for those extra seconds. I'm getting hours more battery life in return.
2. I don't notice the difference in screen quality, nor will I miss ProMotion. I don't game on my Mac and there's really no point in nitpicking 60fps or 120fps for scrolling an article. It's not like I'm reading the article while it's being scrolled.
3. Dongle life has been a constant since 2016 for me and so... I already have all of the dongles for everything. Even with the extra ports, I'm not getting Ethernet, nor CFExpress, which are used more by "pros" these days so there's really no point to me. Even if I were to stick with SD cards to try and use Apple's SD reader, it's limited to UHS-II speed so it's still super slow. It's like Apple provided the ports more as checkboxes to tick off rather than to actually support pros.