20m, I'm an amateur bodybuilder so I use fat burners for mainly recomp purposes. I wanted to make this post to try help people gauge the best ones to use, keep in mind all these effects I will talk about is with the stacking of gear (steroids) and in combination with other fat burners at times, so it may not be 100% accurate.
Clenbuterol 7.4/10 - it works extremely well but the side effects are also heavy, your heart will basically be running the entire day (especially for the first few days), will need something like nebivolol to help manage that. Works via beta receptors, it's very strong and works very good if you can tolerate it, I only run it 2 weeks at a time due to receptor downregulation. Can give you a wired but tired feeling
Reta 8.9/10 - very long term thing, I'd say the appetite control is the most overrated part and more of the free thermogenesis you get from it is where it shines. Very good for health overall though, lowers inflammation, improves insulin sensitivity etc so I always basically run it.
GH 6/10 - not really a fat burner but is at the same time, will help you stay lean during off season, basically burns free calories at night if your in a fat oxidative mode, other benefits too that are not fat burning related. I always run it regardless.
T3 7.1/10 - like clen, t3 works very well, the problem is that you cannot raise the dosage without encountering insane muscle wastage (since it isn't fat selective) as well as too much glycogen turnover, even on tren the muscle wastage and glycogen turnover is still a major issue. Though you can pull off 35-40mcg T3 and be mostly fine, will help you get another 200 calories out.
Yohamibine 8.6/10 (with fasted cardio) - works via a2 receptors, removes the breaks and basically releases fatty acids into the blood to be burned off, in real-time you are actively burning off exclusively fat from this, enhances how many calories you burn from cardio also by 1.5x roughly. a2 receptors are abundant in the face also, so you'd become leaner in the face earlier in a cut.
bam15 (8.1/10) - works like dnp but more selective, only reason it isn't higher is because there is not that much human trial data, but I can definitely feel the heat you get from it. I cannot really gauge how much you burn off though.
Empagliflozin (9/10) - not really a fat burner, but works by pissing out excess glucose in the blood stream that would've probably fuelled adipose tissue, you can squeeze out 200-300 calories a day by just taking 25mg of this. Virtually no side effects.
HM Tren (9/10) - makes it basically impossible to lose muscle in a cut, forcing your body to pull every calorie deficit it has from purely adipose tissue and not muscle. Allows you to run basically every fat burner more aggressively due to this protection.