If it fits your needs, you can’t go wrong with BakFlip. I had the G2 on my previous F150 and Ram pickups. I believe the G2 was advertised as weather resistant but not really water tight. However, with some minor mods to the drainage rails I did get a water tight experience, even when going through heavy storms. It is flat out an excellent solution.
That said, it starts at just under $900 and other bakflips can go over $1000. For that price, IMO, the DiamondBack SE becomes a great option. I haven’t owned one but I have friends that have the SE or HD models. Both are outstanding with lots of accessories. That’s currently the route I’m planning to take for my Raptor. As a few others have said, it’s like it was made for the Raptor. It fits with the entire persona of the vehicle. On the downside, it has to be completely removed to open up the bed and it is much more bulky and cumbersome to handle than the Bakflip and similar tonneau covers.