I use legacy vertex lit in my project its very lite and fast for all device but light is not looking good.Other paths deffered,forward and LWRP is very expensive for performance ı think. Note: I use all shader legacy vertex lit,too.
Forward is the traditional rendering path. It supports all the typical Unity graphics features (normal maps, per-pixel lights, shadows etc.). However under default settings, only a small number of the brightest lights are rendered in per-pixel lighting mode. The rest of the lights are calculated at object vertices or per-object.
Legacy Vertex Lit is the rendering path with the lowest lighting fidelity and no support for realtime shadows. It is a subset of Forward rendering path.
Both are fine for mobile, if you want better light and shadows, go with Forward, but if you want just raw optimization, Legacy.