The problem with using a tablet or phone is that it is very hard to type on these devices. The problem with just using a web site is that most of them disappear after a couple years and then your data and log are gone with it.
My preference is to enter data into an easy to use PC version 1 time. Then from there upload it to web sites so I can share it and to my tablet so I can reference it when I am at a dive site. I am not looking for complicated. In fact the opposite. One easy entry into one program and then an easy distribution of that data to other sources. When this can happen, I will praise the program and the individual that authored it. Having it on my PC also allows me to back it up as part of my regular backup routine.
Thanks,
Bruce