In order, I'd say San Martin are the best quality, followed closely by Cronos - but these are also more expensive, anything from £150-£300 depending on model. Then you've got Seagull at about £100, who have been making watches for the Chinese military since the 50s. Between £40-£100 you've got brands like SteelDive and Pagani Design.
I would start with something like
this from Steeldive - it's based on a '70s Seiko made famous by the character Captain Willard in Apocalypse Now. It's also known as the 'turtle', after the shape of the case and is very comfortable to wear. The movement is an automatic Seiko NH35 and it has a stainless steel case and sapphire crystal glass. For £48 delivered to the UK, it is a bargain!
AliExpress have sales every few months, so sometimes it's worth waiting to get good discounts.