FP1 Old, no update to Android 5 ever. Its USB port tends to break. Mainboard and battery are expensive, the display is often sold out, fixing a FP1 is often not cost efficient, without an extra case it will get damaged quickly. Even open and closing the phone a few times damages its plastic rim. It's a normal, older MTK phone with a few "fair" minerals inside.
FP2 Some on-going software/hardware glitches (the worst one, that is not on the official or unofficial list is random crashes of the whole phone, not sure if this one is fixed yet. Just reading the forum it looks like there is something wrong with the modem and/or the antenna in some devices). The phone is modular, most parts can get exchanged. Android 5 and Android 6 is out for other phones with the same chipset. Currently monthly software updates (yes, that's a good thing), the camera could get better quickly with an easy snapin replacement, a pretty, but not prefect case comes with the phone. According to some posts here all T3G minerals were included in some parts, but I haven't seen prove for that down to the part level. I think @Johannes listed something somewhere here in the forum (I found the link, so far, there is still no parts list for that.)
I don't think you will get a straight answer here.
But let me ask a question: How urgent do you need a phone ... and for what kind of use?
We all could talk for ages about the FP1 and FP2, but it the end it comes down to what kind of tool you need to get through your day. I figured out after some time with the FP1 that I don't need a smartphone daily at all, but for other people this does not work at all. It's easy to get sucked into the mobile always-on world with its siren-servers calling out. Just take a subway and look around
The FP2 is much better than the FP1. The software seems to have some glitches (just check the forum) and the Changelog is not very clear about what the problems are and if they are fixed or not. Currently they are getting better with the updates and fixes, but it's not perfect yet. There are "better" Snapdragon based phones out there (battery, camera), but the FP2 is the best modular LOHAS phone. You can even build your own rom for yourself (and only for yourself) if you like to geek. If updates keep coming in, the FP2 (with a new camera module) could be better in the future than many of those fancy locked down phones right now. But even ZTE and Google open up their phones a bit these days, at least software-wise, not in terms of supply chains and T3G.
But if you really depend on your phone every day, an iPhone with a good protective case with extra power and a good always on backup system might be more reliable and more stable ... if you don't like to think about technical issues and updates and just want a phone that pretty much works "perfect". (Or just doesn't give you a chance to make mistakes )
Just my ideas for your thoughts of course.