The answer to this question depends a lot on your skill level.
You say you want a ski that does a little bit of everything, so I'd recommend a ski with both camber and rocker, but you're going to have to balance length and width based on how you ski. The shorter ski you get, the more control you're going to have on the downhill, but you're going to have to go wider to get the float you need to support 90kg plus a backpack (you need to factor in the weight of your gear and backpack when shopping for backcountry skis).
I'm 188cm, but not even 75kg, and I ride skis 210cm long. They are amazing for staying afloat in deep snow, and climbing steep slopes with full skins, but I'm not as strong a skier as I used to be, so I struggle a bit on the downhill in the glades trying to dodge trees. My next pair will probably be 170cm at the longest for tight turning (and slightly slower descents) with a little more rocker because I tend to stay in deep snow. I probably won't enjoy the uphills as much, but if I get a wider ski I should still be able to float fairly well.
If you're really not sure what kind of ski to get, then go for the best deal, riding your skis is really the only way to learn what kind of ski you really want or need, but if in doubt, just pick something whics seems to be a balance of everything (rocker, camber, radius, width), and use them for a season, from there you'll be able to discover what type of skier you are and what type of ski you'd need.