>>2039060 (OP)Second hand Brompton if you can find one.
I've had a >Decathlon foldable and a Brompton.
The Decathlon had a big hinge in the middle of the tube that made folding annoying. You need a larger "footprint" to fold it, so to speak, so if you use it as a first/last mile during a commute that includes a train or subway ride then it can be a problem depending on how crowded the platform or the wagon is that day.
The Brompton easily solves that problem because you can just "tuck" the rear wheel and stand over the bike while it's only half-folded. The rear wheel just takes two seconds to fold and that is by far the best feature on any Brompton. Or fold it completely if you really need to completely reduce your footprint. HOWEVER the shifting sucks. It has always sucked and all the fanboys telling you "you're just doing it wrong, you have to pedal backwards then stop pedalling then put one hand behind your back, poke your tongue out and scratch the tip of your nose with your other hand and it shifts just fine" are coping with the fact that the shifting fucking sucks.
On older versions, you just have your hub shifter and with how little difference it makes you're almost better off treating it like a single-speed bike. If you actually ride a lot then you should have the legs to deal with that easily. But these are not made for cyclists, they're for commuters who can't climb a four degree gradient, so Brompton has done everything they can to overengineer a double-shifting solution with hub+cassette that is really not necessary because heavens forbid you have to put any effort into your cycling.
A brand new Brompton is not worth the money (since you'll be in no small parts paying for their pattented suck-ass shifting technology) and getting locked in their proprietary parts system sucks. Finding an older one for much less solves the problem.