This topic is too big, to give a comprehensive reply...but what is always true: "don't trust any label or imprint"!
Just a short note, from what I have experienced so far:
1. OSRAM (2700K / 8.5W / 68mA)My experience:- OSRAM does not last very long, but you can repair them easily
- the power factor is very bad: 0.59 PF
2. NEDIS (2700K / 11W / 70mA)My experience:- I am quite happy with this brand
- the power factor is not that bad: 0.89 PF
3. OSRAM filament Cool White (4000K / 11W / 52mA) My experience:- filament means = beyond repair (at least for me!)
- as it is "cool white" the power factor is very good: 0.95 PF
(the best power factor for LEDs I have seen so far)- in contrast to "cool daylight filament": 0.61 PF (6500K / 10W)
- and in contrast to "warm white filament": 0.59 PF (2700K / 11W)
...i will probably check some more led fluorescent lamps in the future...
Here my two G13 (120cm) LED fluorescent lamps as a comparison: a cheap one from "Müller Licht" with 0.54 PF and a more expensive one from Osram with 0.92 PF. When I am not mistaken the Osram was the same price as the complete LED fluorescent lamp from "Müller Licht" in an IP65 housing with 2 x G13, 120cm; of course not the best build quality, but you get what you pay for... ;-)
Müller Licht G13, 120cm (4000K / 18W / 151mA)with the worst power factor for LEDs I have ever seen: 0.54 PF
...and here the whole lamp with 2 x G13, this time with a power factor of: 0.58 PF for both LED fluorescent lamps in the IP65 housing:
OSRAM LED SubstiTUBE STAR ST8S, 120cm (6500K / 16.4W / "no info" mA)with the 2nd best power factor for LEDs I have seen so far: 0.92 PF
Cheers!