This is a million dollar question. And, comes down to your needs/wants/usage.
If Nothing stay with their July release cycle for their ‘flagship’ devices, we’re 11 months away from seeing the Nothing Phone (3). And, the question is… would you be willing to wait that long for the device? If the answer is ‘yes’ then wait for (3) as it’ll be Nothing’s latest and greatest for the time, will likely be powered by AI and feature the latest/greatest Nothing design.
If you can’t wait until July 25 or, at least to early next year, then I’d suggest going with the Nothing (2a) Plus. Again, you’re getting Nothing’s latest/greatest design, software + more. And you’ll be a Nothing user much sooner.
If the goal is to be in the Nothing ecosystem but, you can’t wait until the (3) and you’re okay with the limitations that come with the CMF Phone (1) then I’d go for the CMF Phone (1) as an interim phone until the (3) comes to market.