nvidia very good for gaming, i use nvidia has long 
For gaming purpose i will vote nvidia, for mining i will vote amd
can u give me recomendation NVIDIA card with budget around 50$
i want to build a gaming PC, or is that 50$ not enought??
$50 for a graphics card for gaming is not enough
You need a bigger budget.If you want to game, your graphics card is probably the most expensive component in your pc.