I personally prefer the D5 Vario pump - the non PWM version with manual 5 step control. Though the PWM version is also fine. They do not need to run at over 50-60% for most loops and are very quite (near silent) and reliable.
For convenience I prefer the cylinder type of reservoirs. they are good looking, easy to place, easy to fill and drain.
this is what i have in my build:
https://www.ekwb.com/shop/ek-d5-vario-motor-laing-d5-vario-motor
https://www.ekwb.com/shop/ek-xres-100-revo-d5-acetal (i use the small since i have mini ITX build).
You can use any of those as well :
https://www.ekwb.com/shop/ek-xres-140-revo-d5-pwm-incl-pump
https://www.ekwb.com/shop/ek-xres-100-revo-d5-pwm-incl-pump
Depending on where you live, you can get a cheaper deal. for example:
https://mayhems.co.uk/pumps/laing-d5-vario-8-24v-pump-w-tach-cable-option-mcp655-and-etc./
Same pump at much lower price and even with the top that you are going to remove, but nice to have. you can use it with the res i mentioned above.