For building your own, step one is to decide on your budget, and step two is to go to Logical Increments, look up your pre-determined price range, and bam - you now have your complete list of parts. To spare yourself from wasting an unnecessary amount of time and energy, it's important that you complete step one before starting step two. Realise that what's available in other price ranges than your own is entirely irrelevant to you.

Logical Increments does a really good job of picking good, sensible parts for each price range that are great value, and which is guaranteed to be compatible. Unless you already know a lot about hardware on a technical level, it's like another full-time job trying to compare every available piece of hardware against all other available hardware, especially when much of the available information is untrustworthy or biased, is marketing fluff, is misinformation or superstition, is generally esoteric, and if you seek the advice of "enthusiast" communities, you're just going to get parroted answers from people that can't actually tell you the reasons for any of the answers they give you, because they don't know themselves.

You can of course replace any recommended component in your tier, if you want, but if that means doing a lot of research, then you should realise that it's probably more efficient to just spend that amount of time working a paying job, and then either upgrade the part in question to the next tier (but make sure it's compatible with the rest of your build!), or set it aside, and upgrade that part in a few years from now. Remember that being able to easily install and replace parts is one of the pros of PCs, and that you're doing it wrong if you're trying to find or build some kind of "forever pc" that will "last". There is no such thing, and you will just end up paying overmuch for less compute, by chasing that idea.

And if you don't like the capability of the parts in your budget tier, then that means you should set aside the amount of money it would have cost, and make a feasible plan for how much money you will set aside each month and add to the pool. Then you will know how many months until the next budget tier is in your range, at which point you should come back and evaluate if that tier is then sufficient for your needs, or if you should save up for the next tier instead.

Just know that value drops off fast the higher up you go, so saving for a higher tier is rarely worth it. High end computing has incredibly poor value, so don't look jealously to that. Mid range is where you're getting the most bang for your buck.

And of course, if it turns out that the budget you set for yourself actually gives you needlessly high end hardware, then go ahead and down-grade to a lower tier, and spend that extra money on ice cream, or a loved one, or a charity, or set it aside for future upgrades.

EDIT: If I was building a PC right now, I would be taking a serious look at the second-hand market, which would be a first for me. That's a possibility for you as well, though that will obviously require a lot of research on your part. It may be a decent compromise to get everything new, except for your GPU and/or RAM.