My next phone will be whatever Google's next flagship phone will be, assuming they fix USB OTG, LTE and microsd-slot. Or some other vendor that is smart enough to use vanilla Android without any "product differentiation". I don't want any custom UIs like HTC Sense or Touchwiz, non-uninstallable bloatware (looking at you Samsung: Kies, ChatON, etc.) and app-breaking UI 'enhancements'.
LTE is currently a negotiation point in hands of carriers. The price of supporting LTE would be no timely updates (see also Verizon and Sprint Galaxy Nexus). This is something that Google will not compromise about.
MicroSD is a slightly different story, it has several problems:
UX ones:
- most users are confused by two separate storage pools (see the confusion: "I have XY gigabites free on the phone, why can't I install this app?") - the SD card has to be unmounted, when the phone is attached to the computer - that means killing everything, that was launched from the card.
Technical:
- The MicroSD performance is inferior to eMMC.
Legal:
- You have to license FAT32 and exFAT (for SDXC) from Microsoft. (Yes, I know that it is technically possible to use different filesystems with SD cards - but that is a decision that would not go very well with mainstream users who just want to connect the phone to their Windows or Apple computer).