re: I have a 5c, should I get a 6s or 7?

Considering that you seem to be looking for a reason to get the latest phone, maybe fixing your 5c and waiting for the 8 would be better. The 5c is old enough that you can probably get the screen fixed for $100 or less. The 8 coming out next year is supposed to be a pretty significant change. Wireless charging and edge to edge screen giving you more screen size in a smaller form factor are the most common rumors.