tl;dr: All other methods are either less precise, more prone to user error, or too impractical/expensive to do daily. It doesn’t matter which scale you buy. Just get any $20 model from Amazon. No smart/body fat sensing required. All scales are imprecise. Still good enough.
Yea, yea, the scale isn’t perfect. Most scales aren’t that accurate. Weight can fluctuate quite a bit and most people are much heavier during the day or in the evening than they are in the morning.
Some people like measuring their waist circumference and claim that this is more reliably or accurate for them than scale weight. I measured both for years and this is absolutely not the case for me.
I went with pounds and centimeters because those are the smaller units (compared with kilograms and inches) and therefore make changes sound more dramatic, ha. Both weight and waist measurements were typically taken in the morning after using the bathroom but before consuming anything including fluids. Note I didn’t always use both scale and waist size hence there are some gaps.
But the waist circumference measurement is way noisier. Within a few days I get inaccuracies of 5 or more centimeters at any waist size ever recorded, e.g. from my thinnest to my fattest. So it’s not just that it’s inaccurate when you’re very obese. It’s never very accurate. 5cm noise out of 110cm is 4.5%. There are nearly 10cm of noise in early 2017 near my all-time low making for 10 out of 95cm noise, or over 10%!