So yeah, Android sucks right now.
No, your device sucks, not Android.
Android UI is fast and fluid with no lags (since JellyBean), ecosystem is excellent (high quality apps), no need to restrict any background processes (especially Google Play Services), memory management is excellent and keeps at least 12 recently used apps in memory even on 1GB RAM device (they open in a flash), multitasking is very easy to use (especially on Sense ROMs and Lollipop) and the battery life since KitKat is great (1% per hour on stand-by, 6-7h screen-on time, 18h+ normal use on both HTC One and HTC Desire 601). I have used WP and BB10 devices, none come even close. iOS is the only comparable performance and ecosystem alternative, but with some limitations (fixalbe with jailbreaking).