The best replacement for runtastic is runkeeper.

The best alternatives to runtastic are rated as following:
★★★★★  runkeeper
★★★★  endomondo
★★★  mapmyrun
★★  strava
★★  runmeter
★★  mapmyride
★★  mapmyfitness
★  walktastic
★  sports tracker
  cyclemeter
  micoach
  nike+ gps

Your alternative for runtastic is not listed? Suggest!
Speaking about runtastic, one probably shouldn't forget about polar h7.

Other search terms related to runtastic and their ratings are:
★★★★★ polar h7
★ myfitnesspal
You have in mind a companion for runtastic and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of runtastic in all years. Click on graph for more.
runtastic
runkeeper
endomondo