if they were my tanks:
55g: filstar xp3, won pro 200w
38g: emporor 280, VisiTherm 150w (current)
25g: penguin 170, ebo jager 75w
20g: penguin 125, ebo jager 75w
10g: penguin 125, ebo jager 50w
6x turn over: in my tanks, seems to work good for me, no problems yet. the only reason for the 125 on the 10g is that i dont like the mini.
3w/g: my tanks stay plenty warm, 5 seems a bit like overkill.
a sponge prefilter on the intake should make any hob
or canister fry safe id think.