Believe it or not, I just use a 3-ring binder. I don't have any special forms, just lined paper, and my log format has very slowly evolved. It is probably still doing so. Periodically, I move sheets from the binder to a document wallet for archiving. (I like 8 1/2 x 11 yellow "legal" pads, as I find the color, with blue ink, very easy on my aging eyes, and the paper is heavier than notebook filler so it won't tear out of the binder. I tear off and 3-hole punch my sheet at the end of the brew day. Kind of a ritual end of the day when all's put away!)
Incidentally, in the early 90s I used some of the very early software from time to time. Like all other documents from the era, those logs are long since lost to the floppy oblivion of unreadable formats. Today's tech will follow. Yay, paper!