I use a Z6i 2.5-15 x 56 with dot illumination for stalking and high seat work.
When stalking I usually keep the manification at 6x or 8x but the 15x is handy on occasion for final checking of the target - if there's time to adjust it of course.
It has prevented me from shooting a button buck out of season (I spotted the buttons) and/or taking a trophy Chinese Water Deer (I spotted the longer tusks) when I only wanted a cull animal.
It's not too heavy for stalking and the little bit extra light gathering can help with those last-minute fallow that you always seem to spot from a high seat too.
As Mauser243 said though, it's each to their own, if you can have a look through a scope before you buy then do so.
Better still try one from a high seat on a borrowed rifle (in line with legalities of course) and gauge what suits you.
If most of your shots are snap shots then maybe a fixed mag is better?
If you shoot at longer distances or maybe just want to see the target a bit closer up then maybe zoom fits your bill?
I think variable mag and a big (ish) objective works for me, but it might not for you.
If it's just for high seat work I wouldn't imagine weight matters too much unless you have a several mile uphill hike to your high seats.
ATB
Geoshot