I live in Malta and my very first computer was an Atari 65 XE which was around 1990/1991. It was awesome, I still remember the red label cassettes that came with it which had game compilations and I had some other games like Henry's House, Ninja Commando, Joe Blade II, James Bond (that sucked) etc on cassette tapes and then had Pac-Man, Tennis, Pitfall II and Mario Bros on cartridge. Also had two 7800 joysticks. I loved it but I was always secretly jealous of my Amiga owning friends and got my parents to buy me an Amiga 500 Plus in 1992.
I would say the C64 was better supported also because it came out with 64KB ram, no less. Granted it came out a couple of years after the Atari 800 when ram was more affordable but still, developers would have probably been making games to support the minimum spec 16K Atari whilst games for the C64 were developed for a 64K machine - The result better looking games and I am sure that helped sell more systems. Also, when comparing specs especially that 64K ram I believe the C64 was cheaper than the competition.
The 8 bit Atari's are very solid machines but then so are the C64's though many these days seem to suffer failed PLA's and SID's which is a shame. I got back into Atari 8 bit in the last year or so, I resurrected an Atari 600 XL I had for ages and upped it to 64KB but for some reason although games on cassette and cartridge work fine for some reason floppy disk does not work using SIO2SD so I bought a 65XE (Yayy just like 1991) and that is great aside that I had to change some custom chip which is prone to failing and affects the graphics in a small percentage of games (i forgot the name of the chip).