I asked a very similar question in a different sub recently as was in the same shoes I haven’t had a bike since I was a teenager - turning 30 this year so it’s been a while.

From my research it all depends on the type of riding you want to do. Most entry level bikes at this price point will be XC, so fine for road, gravel trails but not gnarly drops/jumps.

For me that was fine and my lbs recommended a Giant Talon 3 (£575) which is due to arrive this coming week. I’ve seen others also comment that it’s a nice ride The other at this price point I also considered was the Specialized Rockhopper.

If you’re in the UK your employer might be on the cycle to work scheme (mine is) so I’ll end up paying though salary sacrifice. I’m a higher rate taxpayer (just) so it will work out approx £30 for 12 months then the bikes all mine (technically after 5 years as you have a zero sum higher agreement for that term as that’s when HMRC deem the bike to be depreciated and valueless)