It's not hard to build an accurate rifle these days, but it's much harder to build an accurate rifle that feeds from the magazine properly, that feeds well in virtually any conditions even if with external forces applied to the magazine, that has a magazine that locks in solid but is easy to change and that doesn't fall out, that has a trigger and safety that works in virtually any conditions, and that puts the first shot from a cold, clean bore in the same hole as the 20th shot from a fouled, hot bore. As others have said, decide on the use and then find the best receiver you can afford to do that job well. For example, do you want a trigger safety or firing pin safety? Do you want 60 degree bolt throw or will 90 degrees work? Do you want push feed or CRF? Do you want to run a magazine, and if so what type? Do you want to swap barrels yourself or have a gunsmith do it? Do you want an integral recoil lug? How about an integral rail or will you use bases or screw on rails of some sort? Do you want a pinned rail if that's the direction you go in? Is weight an issue? How about corrosion resistance? Lots of things to decide before you land on a brand.
Don't forget that there are some turnkey options too, but don't assume that they're all fully vetted. I'm at the stage where I have zero interest in having a gunsmith build a custom rifle for me (revolvers are a different story), but I get why people go that route. The main reason is that you can't buy exactly what you want or can't easily change what you can buy. I had Bowen Classic Arms convert my Ruger Super Redhawk Alaskan .454 Casull into something I couldn't buy and certainly couldn't convert myself so I do get the appeal of a quality custom that works for your intended use. I have a custom Kimber Talkeetna hunting rifle that I did a fair amount of work on myself, and my gf's Kimber 84M is at Proof having a CF barrel fitted. I'll be inletting a custom fiberglass/CF stock once I get the barreled action back. It's satisfying to take a factory production rifle and upgrade or improve it by adding useful features or simply making it perform better.
I've only ever bought one custom action and it was a Badger Ordnance M2008 which was kind of an AI rip off. I had a Krieger barrel and AICS stock for it but never got it built. I sold off the parts at zero loss so all's good. I've had two Remington 700 actions blue printed by Krieger and had Krieger barrels installed. Those rifles shot really well but I sold them once I got Accuracy International rifles. I hope this project works out for you and that you report back on what you end up choosing.