The Commodore 64 is the best selling 8-bit computer in the world. Nobody really used the Spectrum outside the UK and eastern Europe.
I was planning on buying one, but ended up with a used VIC-20 instead.
ZX80
ZX81
Spectrum (original)
QL <- the best less known computer of all times
Spectrum+ (first one broke and I still had a lot of small programs for it)
while living in Italy (please read as not UK, not Eastern Europe) and there were at the time lots of (italian) users besides magazines, clubs and what not about them.
The C64 came a little later than the spectrum (a question of months, but those were fast moving times about computers) in 1982, and everyone that already had a computer in 1981 were loosely divided in two:
1) those that had a ZX81 before all went for the spectrum sometimes even pre-ordering it or having it bought in the UK
2) a number of the VIC-20 users (that frankly was worse - keyboard aside - than the ZX81) went for the spectrum
There was also a huge difference pricewise, the Spectrum was around 400,000 the C64 was 973,500 Lire (think of 200 Euro vs. 500 Euro).