The best replacement for atmega8 is atmega328.

The best alternatives to atmega8 are rated as following:
★★★★★  atmega328
★★★★★  atmega88
★★★★  atmega168
★★★★  atmega8l
★★★  atmega8a
★★★  atmega16
★★  atmega32
★★  atmega48
★  atmega8u2
★  attiny2313

Your alternative for atmega8 is not listed? Suggest!
Speaking about atmega8, one probably shouldn't forget about cc2500.

Other search terms related to atmega8 and their ratings are:
★★★★★ cc2500
★★★ arduino uno
★ lm35
You have in mind a companion for atmega8 and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of atmega8 in all years. Click on graph for more.
atmega8
atmega328
atmega88