The Rockshox Domain is a great fork for the money at the moment, it’s on offer in lots of places for around the £360 mark.
38mm stanchions, Debonair spring, and whilst it has the Motion Control damper that can be upgraded when you’re ready (and if you feel you need to) to the Charger 2.1 damper. It’s a baby ZEB really, albeit 250g heavier than one of those.
I had one on my Jam2 6.7, and it’s now on my Turbo Levo (still got the Jam2 as well) and the Jam2 is running a Rockshox Silver 35 TK which is fine for trail riding.
Keep the travel and axle to crown size the same as your current fork, and you won’t go too far wrong. I put a 29er fork on my Focus, and run it as a mullet, makes it a much more playful bike in my experience.