Fyi the lily 58 has space for the number row at the top. You can also build a number pad that sits between the halves. It's all wireless and still takes less room than a standard layout.

But anyway, you choose the layout that works for you. That's the whole point of ergo mech keyboards. Lots of great open source software exists to choose and build exactly what you want with no compromises.

I think it's either money or time!

I took the middle road. Like you, I didn't want to / couldn't afford to spend huge amounts just to figure out what worked for me, so I spent A LOT of time in research mode. Subreddits, YouTube videos, Discord servers, the works. All to try to figure out what appealed to me. But I did end up spending more than I expected I would when I started.

The switch thing was a challenge. The keyboard switch testers I've tried haven't really done anything for me. I think maybe it's because I need enough of the same switches to actually mimic typing on to get a sense of how I might feel about a full board of those switches— just the one didn't really give me a full sense. Plus, there are a few other variables that come into play— keycaps, whether you've got any dampening/foam on your board etc. That's not to say you shouldn't get one. Something's better than nothing.

There are two things that really got me started on my interest in ergomech boards: a Vinpok Taptek (cool board but hella clicky for my tastes) and the Textblade (vapourware, but got me thinking about the smallest most practical keyboard I could get my hands on). So I knew I wanted something quiet, and I knew I was open to a less than usual layout/design. I think I may have even seen a split keyboard in the Textblade forums, I think it was an Ergodox or a Moonlander. From that, I ended up with my first board— a Lily58 with rotary encoders. Had someone build it for me, and I was happy... for a while. But the Lily58 isn't the most portable split, so I kept browsing.

Since then, I've picked up a wired Corne, an R2G Corne (relatively cheap, and easy to assemble), and a wireless Corne (had that prebuilt for me; no more TRRS or USB cables to worry about!). I could have stopped there, but I really wanted to know what it took to actually build a board from component level, so I bought an Aurora Corne kit and built a wireless 5x3 Corne. This one is the dream, and because I built it myself, it was cheaper than any of the other boards I bought prebuilt. Switches I love (Alpaca Silent Linears), keycaps I love (XVX profile, which I'd never heard of in spite of browsing a tonne of subreddits, ogling other people's keebs and asking what keycaps they were sporting), and eminently customisable (I just recently upgraded to 1500mAh batteries), all in a reasonably small, portable package. I reckon it's my endgame. It is. I still do browse on occasion, but I have no need to acquire/build another board. Not at all. Nope.

I mean, I did see an interesting Centromere Mini build the other day. But no. I'm sorted.

So, the takeaways:

• Figure out any preferences you might have, including any environmental considerations. Will you need to use your board in a quiet space? Will clicky switches get you murdered by loved ones or colleagues? I'm unlikely to go for low profile Chocs simply because there isn't (as far as I understand it) such a wide range of affordable silent low profile switches, which straightaway helps me to narrow down the kinds of builds I might be interested in.
• Prepare to do a lot of reading around (and YouTubing— there are lots of people on YouTube reviewing switches and things) about the various different components you might want for your ideal board. But remember, no matter how opinionated anyone else might be, your tastes are what matter.
• Find the cheapest way to test out a few staples (Cherry MX reds, for example?) and try to judge things relatively from there. Keycrox in the UK offers sample bags of switches for testing; I'm not sure about Europe based equivalents.
• I don't know whether you shop Amazon or not, but you can probably find switch testers there. You might also be able to test and return a few different boards via Amazon to help you zero in on what you might want.
• Maybe allow budget for a few different variants of cosmetic elements? Having experimented, I know I'm good with XVX, DSA and XDA keycaps. There are others I'm not nearly so comfortable with.
• Last thought: they don't happen that often outside the US, but you might benefit from heading to a keyboard meet-up if there's one near you within a reasonable stretch of time? https://kbd.news/meetups

Hope that helps!

Since you're looking at non-ergo mechanical keyboards, you have way more options and flexibility.

I would get a quality hotswap board (Keychron boards are the usual recommendation, if you go Aliexpress you can find cheaper options too) and a set of any switches you like. Switches maintain resale value well (some even raise, because broken in switches tend to work better than non broken-in) so get a set you're interested in, daily drive it for a bit, and then see what you'd want changed.

You can also think about your current keyboard setup, what you like about it and what isn't working for you.