Scales are fine. Syringes are fine. Drops are not fine.
If scientists in labs and doctor's injecting us full of stuff use syringes and pipettes for measuring, then I'm sure it's fine to use them to measure your e-liquid ingredients. When I was in biotech we were told not to over push the syringe or try to get the last little bit out because they are made to take into account the bit left in the needle. Take that FWIW. No idea what kinda syringes you're using, but we never used any kind of extra force or tricks to get the last drop out of the needle.
That being said, I wouldn't go back to syringes and pipettes if you paid me. Clean up is 10K times better with a scale (because it's practically nonexistent) and it just seems faster and less hassle to me. I use a 'cheap' scale and it works just fine for my needs. Anything less than 0.03 g (weight of an avg drop in my experience) doesn't seem to register, but I know that and take that into account when I weigh. If I could afford a lab scale, I'd love one, but I can't and I love what I have so I'm not sweating it. I have the etekcity pocket jewelry whatever scale and the AWS lb 501 and there are benefits and drawbacks to both. The etekcity is more compact, lighter, and has the ability to turn the auto shutoff OFF, but the AWS plugs in, feels like a higher quality build, and is probably (haven't tested) more accurate.
This is DIY e-liquid; it's not rocket science or breakthrough medical research. Either way you go, you're gonna be fine as long as you're careful and consistent. It's just what works for you. And isn't that the beauty of DIY in the end anyway?