Heater? or Heather(s)

[Metrontech]

OK, so I have 4 Eheim Jager heaters

100W
150W x 2
50W

All of these are so inaccurate and now I can't maintain the temp in my tank

So now that I am in the market get a better setup for my temp control I could use some help

Do I run 1 in the sump and 1 in the display?

Or 1 in the sump...or 1 alone in the display?

What brand?

Watt size for a 55 display and 30 gal sump?

Tanks again