Well, the ARM ATtiny rival would be this one (8KB Flash, 1KB RAM): http://nl.farnell.com/freescale-semiconductor/mke04z8vtg4/mcu-32bit-cortex-m... I can't come up with any convincing reasons to use an ATtiny instead.
mke04z8vtg4: EUR 6.91, 100 pins attiny10: EUR 0.62, 6 pins
Apart from the factor 10+ in price difference, I know which one I'd rather solder...