Backpack, truck camp, hunt from home -all depends on what I'm hunting, when I'm hunting, where I think I need to be, and what I'm in the mood for.
I do tend to backpack in for elk more than other animals because may of my best elk spots are too complex to get to as an out-and-back day hunt. I do some truck camping as well though.
Bear hunting could be any of the 3 and I'm more prone to backpacking if I know I need to be in one area for a couple of days, though I have no real need to "go deep" for bear hunting.
I always hunt deer during the late season (CO 3rd rifle) when they are migrating or already in their winter range which is effectively all front country in my area. I tried backpacking in the past and the juice wasn't worth the squeeze. I now just get up at 3:30 and hunt within a 30 minute driving radius.
For a number of years, I was exclusively into backpack hunting as a purists philosophy and that has made me much better at it, but I've backed off that approach in the last couple of years.