I used to use a LV vernis agenda, but now use an H GM agenda.
One obvious ***** that LV has over H is that their refills can be bought anywhere - you can use all sorts of Filofax refills (date by week, year, notes, financials etc). For H agendas, you are limited to what H provides for agendas, which (IMO) is not a lot. It depends on what sort of H agenda you are thinking of, since the GM has different refill options from say, the Globetrotter or the Vision.
With LV, they all come with a pen loop which you have to either buy the LV pen for it, or go hunting for a small one which can fit into the loop. H has agenda options which come with loops, or with no loops. Depending on which you prefer. Mine has no loops, so I don't know if all pens will fit into their loops. You can of course, also buy an H pencil or pen for the loops.
That said, I prefer my H agenda. Not just because it was cheaper (!!!) than the LV vernis, but also because the leather makes me happy. I like holding nice leather in my hands, and it smells really good. The vernis felt like plastic to me sometimes.
Also - because H refills come in a little book (which you simply slot into the hooks in the agenda), they are easier to write in. With LV, I constantly had problems when writing on the back pages because my hand would hit the binder rings and it made writing awkward.
Though I wish H would have more refill options, I still prefer H... I don't really need different types of date-by-date refills (one week on 2 pages is more than enough for me). My GM is two-loops, so I have a second hook for a blank notebook which I use to scribble random things. It really suits all my needs... did I mention it smells nice too?
