Multipurpose day packs have a wide range of sizes based on personal preferences. I pack more stuff than many so for a number of years a 50 liter pack has been just right. Most times it’s not nearly full, but there’s room to add some bulky fleece, photography gear, fishing stuff, cooking gear, or whatnot. It’s big enough, while being much more comfortable than a full size heavy duty load hauler. Mine stay packed all the time so going out to hike, fish, cross country ski, snowshoe, scout, shoot varmints, deer hunting, or just about anything in the Rocky Mountain states is a simple matter of grabbing it and going.
My bag is the discontinued heavy duty Bomb Pack made with 1000 denier fabric, but it’s similar in size to the Mystery Ranch Bridger. On sale the Bridger is in the price range you mentioned, but I’d look at the used market - many people buy an expensive pack thinking they will use it a lot and it sits in their closet. Over the years I’ve picked up a number of $400 packs on eBay in new condition for under $100, but make double sure it’s the correct size, correct size belt, and correct size shoulder straps, not to mention look over every photo for anything that doesn’t look right.