Hi there,
So , “Better” depends on the job. MG24 absolutely has a very nice ‘out-of-the-box’ story for Zigbee/Thread/Matter (and even CircuitPython).
But on raw efficiency, nRF54L15 wins the common cases: ~3.3–3.4 mA RX and ~4.8–5.2 mA @0 dBm TX, with ~0.8 µA System-OFF + RTC. MG24’s own datasheet lists ~4.4 mA RX and ~5.0 mA @0 dBm TX. Also, 54L15 does include 802.15.4, so Thread/Matter aren’t off the table. Pick the part for your constraints—ecosystem speed vs. lifetime on a coin cell. 
Compute & headroom:
nRF54L15 runs a 128 MHz M33 (+ RISC-V coprocessor) with up to 1.5 MB NVM / 256 KB RAM. MG24 tops out at ~78 MHz M33 with up to 1.5 MB / 256 KB. If you need more CPU cycles per joule, 54L15 has the architectural advantage.
MG24 has SKUs with +20 dBm—fantastic for range, but you’ll pay for it (~156 mA at max power). If you don’t need that PA, the comparison should be apples-to-apples at 0 dBm.
So is MG24 “more favourable”?
If your priority is quickest path to Zigbee/Thread/Matter and Python-based prototyping:* sure, MG24 is easier out of the gate for now. 
If your priority is battery life for BLE-centric sensors/trackers, plus more CPU per µA: the nRF54L15 is hard to beat right now. 
I can say though at 4-5 weeks the info is avalanching with updates coming in a timely manner. Giving it time to marinate and propagate you can’t beat the support they offer over the other companies.
GL 
PJ 
more to come, forsure from the NORDs…