The last time I treated my wife's log cabin workshop (she's not a woodworker unfortunately) I used a Sadolin product that was a preservative but went on with a coloured translucent finish. Some preservatives look like paint, which I don't like, this was more like a stain. Does that make sense?
No much help really as I cannot remember which type it was but got it from a trade paint place near me, they had a colour board. We chose green, it looks good needs re-doing about every three years. I brushed this on. I have also tried the Ronseal you spray on and is garden friendly. Really easy and quick to use, as long as you immediately clean the sprayer after each use even if you are only having a brake for a few minutes as it clogged easily, but I didn't like the colour very much, more like paint. I have to say though, the speed and coverage made up for the colour. I did seem to use a lot of the stuff though.
Mick