WD Blue 3D NAND is decent, though currently not much cheaper at a glance.
The 860 QVO is an option, but at only ~£10 cheaper (5%) I wouldn't.
Those are all Sata 2.5"
There is an M.2 PCIe WD Blue that is different, but has the same brand, because WD can't do more than about 3 colours, but I meant the 2.5" ones
WD Blue™ SATA Internal SSD Hard Drive 2.5”/7mm cased | Western Digital | Western Digital Store
Ready for your high performance computing needs, a WD Blue™ SATA SSD offers high capacity, enhanced reliability, and blazing speed.www.westerndigital.com
For internal HDDs, I've found Toshiba N300s to be great.
Is there anything in particular you are looking to store? A fast, modern, 7200RM conventional drive should operate around 150-250MB/s which is no slouch.
I only have SSD storage for OS, Programs and Games. It's pretty much pointless for everything else.
That's what I use my conventional drive for. It would be an improvement to have it on SSD, no doubt.... but, it's a costly outlay for no real necessity.
If looking to spend £200... I would spend the £220 (ish) and get the Crucial MX500 as suggested earlier. Otherwise.... I would be opting for a 5TB+ conventional drive around the £120-150 mark.