If you want some thing better then normal 70cc bike then go for https://www.pakwheels.com/forums/bikes-3-wheelers/186394-eagle-firebird-dg70-bike-thread or Ravi Premium R1 70.
If you want normal 70cc bike then go for any bike. all are good in mileage and durable as well.
All chinese/local 70cc bikes give good mileage equal to honda or less/more then honda depend on engine/riding conditions as well. I have 2006 metro as well still going good. So don't need to worry about that.
Eagle claims 85km average, but i can't tell you about my Firebird average bcoz it is passing through running phase. So far done 410kms on speed o meter.
change your bike oil on every 1000km. do tunning on time and change oir filter when needed. take care of bike use wax or polish and you are all good. Chinese bikes will never refuse you.
Make your choice.
Hope this helps.