Well tiger NDS was free and just a proof of concept. U cannot judge him there. He has a slow but steady update cycle as well. He has never shared many details with me about his plans when I have asked.
With Google taking him off the market we may have to wait a even linger before we see an updated version.
As for NDS4droid it showed up after tigers and is very simillar. Some games work on it differently than tigers though and he has a different control scheme. But he charges more for his emulator than Fpse which is a fully functioning ps1 emulator..
I am not sure we will see an update by NDS4droid.
All of true other NDS emulators are copies of either of these two.
I just wish the devs would give us the option to enable sound. That way if the emulators are never updated we have a chance as hardware improves to be able to run them at full speed....though I think the issue is more on the end of the devs ironing out the kinks .