trial and error is the best way. learn from your own errors. my family in asia breeds exotic fish and have never asked for advice. you are suppossed to learn yourself or you become "weal" at fishkeeping. maybe we are just crazy...
i agree why learn from your own mistakes when you can learn from other peoples mistakes or experiences its a lot easier.
anyway i have used tronic,visitherm,ecotherm,ebo and a few others and they all seemed ok to me.
i have a visitherm and tronic in my tank one at each end plus a spare 200 and 300 and even an extra 150 kicking around somewhere just incase.
its good to have spares
I have a Eheim Jager 200 watt on my 135 and it is able to keep the entire tank at 81F with no problem. But I have a fast current in the tank because of all the plecs. My Eheim 250 was able to take the water temp up to 95F. Good thing no fish were in the tank at the time!!!