How far away from FIRE are you?
If your job did go away in a few years, how willing would you be to uproot yourself and move somewhere else vs. hunker down with whatever job you can find locally?
Is this your forever neighborhood/forever home, or do you plan to move elsewhere at some point?
My view: by the time you are ready to FIRE, you want a paid-off house as risk mitigation.
Pre-FIRE, your focus is on asset appreciation. A house is an expense, and how much its value increases has nothing whatsoever to do with whether you have 0% equity or 100% equity. So you are generally better-off putting your money somewhere where the amount you put in does get you more appreciation, i.e., the market. You can also afford to ride out drops in those investments, because you have the big cash cushion of your job -- IOW, generally speaking, you can afford to take the risk that the leverage of a mortgage provides.
By the time you FIRE, though, you no longer have the safety net of the constant cash stream. You still need growth in your assets, but you also need to protect against a big downturn. And one really, really good way to do that is to minimize the amount you need to withdraw each month to cover your basic expenses by having your biggest monthly expense already paid off.
My preference is to take a mortgage that generally aligns with your planned FIRE date. Obv there will be exceptions (if mortgage rages are super-high or super-low, for ex.). But that would be a reasonable way to approach it to balance the risks.
But the risk with buying a home while you're still working, of course, is what happens if the job goes away before you're ready to FIRE? We had that happen a couple of times, and one time that meant moving to another state and then hanging on to a house we couldn't sell for over a year and ultimately taking a big loss on it. We knew other people who were rooted in the community and unwilling to move who literally ended up delivering pizza, because that was the only job they could find.
If you're willing -- and in a financial position -- to do the hunker-down-and-deliver-pizza route, and this is your forever place, then go ahead and pay cash. As long as you have enough money to cover your living costs out of investments or some BaristaFIRE job, you have the downside covered. OTOH, the less likely that this is to be your forever place, and the more dependent you are on your job -- the more you are in the growth phase trying to get to FIRE -- then the riskier it is to put so much into a home. You're better off taking a mortgage, letting the rest of your investments increase as much as possible, and then sell if you need to down the road.
Or, you know, don't buy at all. That increasing rent gets you something: the freedom to move somewhere else at the end of the lease, with no need to sell or buy and no risk of loss whatsoever. If you are a long way from FIRE and very worried about your job situation in 2-3 years, the last thing you want is a giant debt around your neck.
