Just to answer your question if you ask my opinion there is a huge list of good smartphones out there, but it totally depends on users view which smartphone is best for them. for example, if I'm a camera lover I would love a triple lens camera primary camera + dual selfie cameras. Similarly, if I'm a hardcore gamer Love playing high-end games I would go for smartphones which have good rams like over 6 to 8 GB a good processor and 5000 mAh battery life. On the other hands, if you're more active on social media like facebook, WhatsApp, Instagram, snapchat, etc you will for sure need a good storage phone. The phone which has minimum 64GB inbuilt storage and anything above that is just fine to store high data like pics, movies, videos, etc.
Also, good ram and processor is required for the smooth working of the phone. You cannot do better multitasking with 1 or 2GB ram phones nor you can play and good games on it. Your phone will lag a lot while using Facebook or WhatsApp also, due to less storage your phone will always get filled up very often. I've made a list of top 5 mobiles in 2019 so far trending in India under 30K, Check their specs and decide as per your needs which suits you best. Hope this helps cheers.