I've had quite a few canopies over the years, and seen dozens more. There are lots of brands, but I can recommend a few features that I've found are very valuable.
1. Straight legs. The angled leg ones are pretty common, but you lose a bit of shelter space, and they are tough to integrate into your camp - the legs are always in the way. Straight legged ones maximize shade/shelter, can be easily placed together for a larger covered area and can go tight to a wall/RV/fence.
2. Double-layer cover. You may have to look a bit harder for this, but it's REALLY nice. Most single layer ones, especially white, don't cut the heat of the sun very well. The ones I have now (sorry, can't remember the brand, but I got them at Dick's Sporting Goods) have a colored top layer, and a "silver" inner layer. On a hot day, this makes a NOTICIBLE difference in cooling. Much better shade. I wouldn't have a single layer one now.
3. Integrated tie-downs. Having the tiedown guy lines attached to a sewn-in loop at each corner of the cover makes it easier to securely stake down the canopy, and will resist much stronger winds than just staking the legs. In fact, if I'm expecting weather, I use small ratchet straps, wrapped around the entire corner of the frame, and staked out at an angle. Mine have successfully survived 50 mph winds with this setup!
Good luck.