What should i follow
ui_component form or
php form so my module can work on all magento 2 versions. Or Should i create two modules so they will work on magento 2.0 and magento 2.1?
Any one else have a better solution for that?
Magento 2.0 totally supports UI Component form, it's not a 2.1 feature only so I suggest you use the UI Component ;)
Also you can find the benefits of using the UI components here: Magento 2: what are the benefits of using UI grid components over the standard Grid.php?
Magento 2.1 you should go with Ui Component for grid and if you don't have any customization in your form then you can use Ui component for form too, but if you have any customization or any changes in buit-in form input types you can use normal php form. but as Magento 2.1 has lots of benefits I prefer to use Ui component for more benefits and use you can refere MagentoDocs