A few random thoughts for you: first, powder-wise, who knows. The Alps get different types of snow patterns than the Rockies, often with bigger/less frequent dumps (and less overall snow, as far as I can tell). Moreover, exposure and visibility issues, both a result of less tree cover, make it trickier to predict if and when you'll be skiing powder.
Val Thorens is a great bet for snow, I'm told, but horrible for exposure/wind. If I had to choose a European resort purely based on chances of finding powder, I'm not sure I'd choose the Trois Vals, though better informed Bears might say I'm wrong.
My general feeling is that March is way better than Jan. for skiing at Alpine resorts; I'd probably even choose March over Feb. for skiing in these parts.
As for this: "The reason I was looking at Meribel is because apparently it's all people from the UK so I don't have to worry about speaking any French," I wouldn't worry about English not being understood in a big international resort like this. I would worry about being in a Brit ghetto in a place like Meribel, but that can be the case in a lot of resorts, from Verbier to St Anton. Whatya gonna do?
And for this: "Ideally I want to go when snow conditions are the best. I don't want anything resembling spring conditions," fear not. You've heard me rail on about how misleading Alpine verticals are compared to North America (and if you haven't read my illuminating posts, shame on you). But there is an upside. In the Alps, spring conditions at 1700 meters may well give way to mouth-watering winter snow at 2800. That rock-hard offpiste you struggled down at 9am may be soft and perfect by 3. You'll either need solid mountain instincts or some guidance to make sense of this in just a week at a big resort like the 3 Vals, but it's a constant theme in the Alps.
My final word of advice to you, at least for my current post, is this: If you've never skied in Europe, please suspend all preconceptions about what a ski area is and should look like. In doing so, you will dramatically enhance your ability to understand and enjoy your surroundings. People will be going up the hill on lifts, and descending on skis and snowboards. Pretty much everything else will be different.