WRT Bromptons over the alternatives. It's unfair to assume that everyone is blinkered about Bromptons and simply isn't considering the alternatives.
I've been commuting by bike in London for almost 20 years. The first few were done on a rigid MTB, then a hardtail. Then, once I'd moved out of town and had to get a train, I looked at folders. At that point, I didn't know you could get a full-size folder, until a guy I worked with told me about his.
I looked at everything going and wanted to resist getting a Brompton because they're a little bit sit up and beg, and they tend to be ridden by people with reflective chest bands and trouser clips. Even so, I looked at them plus Dahon and Airnimal before going for a Rabbit.de second hand.
It was a great bike for my needs. Looked like a regular bike, rode like a regular bike and was fast enough for me. The problems arose when guards and/or other passengers got a bit stuffy because they thought I was bringing a 'bike' on the train, rather than a folder.
Unfortunately, I got knocked off that bike, but because I liked it (and it was essentially a Dahon clone) I ordered a Dahon. The seat tube weld started coming apart after about three/four years so I tried to get it sorted under warranty, but this was about the time that Dahon was no longer trading and
Evans didn't want to know about helping me get it sorted.
While I was to-ing and fro-ing trying to get it sorted, I bought an older Dahon SH as it was less than 1 month of parking and tube fares, and I'd already wasted a couple of months not riding.
After about a year, this bike also cracked on the seat tube and was binned. As I never got the other one replaced, I started riding that again and that eventually got worse. The small crack on the weld, became a big crack on the seat tube. And now it's not worth the risk of riding.
So that leaves me where I am now. Needing to buy another folder, but with a lot more experience about the practicalities of doing it every day. I've seen or spoken to plenty of other commuters about their bikes (apologies if I've bored you on the 0810 from High Wycombe) and here are my observations.
Airnimal's folding system is not really suited to commuters, more for storage. Same is true of Swiss Mountain bikes. Anything where the wheel has to come off to fold it hasn't really been designed with frequent folding/unfolding in mind. Birdy's are even more expensive than Bromptons and no less spoddy. Oribikes look great and ride well, but ultimately don't fold as small or as neatly. I'm put off Tern because of the Dahon connection.
So my incoming Brompton has been a very considered purchase - especially as I've never actually wanted to get one, it's just the best tool for the job. For me.