In 2018, a AMD’s Vega 56 and Nvidia’s GTX 1070 would be good picks, and everything from the GTX 1060 and RX 570 and up is viable, but the situation is more complicated than it sounds. AMD’s Vega 56 would be a great choice for mining, if only you could find it for the original target price of $400. But, that’s ol’ setup would mean more costs and lower profitability. In 2020, if you fancy mining with own rig setup and a laptop to monitor your mining with a rig setup of four GPU like AMD RX 570/580, but your can configure it to have a NVIDIA GTX 1070 GPU or 1070 Ti GPU, this would be just great.
Another way of doing it with expensive layout but it will turn out profitable if you mine wisely, you can get a decent desktop or a laptop of a CPU of a Intel Core i7-7700 or Intel Coffee Lake Refresh Processors, you will also need Graphics Cards of Nvidia GeForce GTX 1060 – 1080 Ti or a Nvidia Turing Graphic Cards, you will definitely need a RAM of up to 64GB a Storage space of 2TB HDD and 128GB SSD and a 2TB HDD with 512GB SSD.
For a more mobility, agility, and control, a laptop or desktop connected to a Raspberry Pi 4 with a RAM 8GB, a SD CARD with USB adaptor as most laptops have an SD CARD socket and also you will need a 14TB SSD and a rig with ASIC or GPU.
Be warned that mining, costs more electricity and costs of time of work you put into it, this can only be achieved if and only if the value surpassed more than the costs.