M1 if you can get it under £900 I paid £859 for mine and its awesome, anything over £900 I would wait and see if it drops again as the prices tend to fluctuate a lot lately. Last month when I got mine all the major retailers in the UK (other than Apple themselves) had the base model M1 for around the £859 mark, and I have seen it about 3 months ago drop as low as £818 on Amazon for a bit, but don't pay anymore than £900 for it as you'll kick yourself when a sale inevitably drops the price of it in a week or 2 of you buying it.
From a technical point of view what a lot of people are forgetting is that the base M1 has an SSD that is twice as fast as the base M2 version and a thicker heatsink too.
The M2 is faster but it also cooks itself very quick and throttles back to not much faster than the M1 and then if you hammer the RAM the slower SSD means that the M2 will show the spinning beachball of death and grind to a halt more often than the M1, various tech channels have observed this behaviour too and in some tests the M1 is actually faster than the M2 due to this.
Most of the big tech channels on YouTube have pretty much said go for the M1 over the M2 due to the cutbacks Apple made to the M2 over the M1, granted that was when there was a £200 difference between the models but as other large retailers often have huge discounts on the M1 the savings over the M2 can be huge and make the M2 look like a rip off by comparison.
With regards to macOS support going forward I wouldn't be surprised if the M1 & M2 series gets dropped together since the M2 is just an overclocked M1 with the Pro Res encoder enabled. I suspect the M3 is where any big hardware changes that will cause future OS updates to drop features will come in.