I use the inkbird and have done for years. Used it for controlling kettle element on my old kit and the moving it to fermentation control of my heatmat. Can only really vouch for this one and still going strong.
The Mangrove Jacks one is a pre-assembled STC-1000, which Inkbird also make. There'll be hardly any difference between them but the Inkbird 308 and others in the series are slightly easier to program because you don't have to hold the set button at the same time as changing a setting and each setting has a name rather than F1, F2, F3, F4.
I have 3 inkbirds that I use for controlling FV temperature, one for a brew fridge and two for controlling water baths / fish tank heaters. They have all been faultless.