Do you include geysers, like Abuse Spring, whose eruptions of world class heights lasted for a very short period of time. Do you include geysers. Do you include geysers, like Grot Yubileinyi, whose eruption would be much higher if they shot straight up instead at an incline. I have included all of the above but if you chose not too you would have a viable but smaller list. Even with that said, determining a geysers height is a difficult proposition.
Geysers tend to have bursts.
Getting a measurement of a burst that lasts a second can be difficult if not impossible. Wind can also shear off the top of an eruptive column making it appear shorter. In my experience measurements by sight or dead reckoning are usually dead wrong, It is difficult to compare the eruption to nearby objects since geysers usually sit on a silica mound some distance from trees or other tall objects. In order to get good measurements one must measure the distance from the geyser to the measuring and observation points. This is almost impossible if one is confined to boardwalks as he should be to protect himself and the thermal features.