Bike rack-roof

Definitely with the front wheel removed. Locking down the front wheel and then latching the back wheel on will hold the bike very stable and with minimal stress.

This is especially important for carbon bikes… most racks where you leave the front wheel on, relies on a clamp that may cause a stress point. I've seen cracked frames from this… Now, there's quite a few good racks that reduces the stress, but if you have an option, why not just remove the front wheel and lock it down that way, removing any possibility of stress.

I have both styles

Mostly use this one: http://www.innoracks.com/details/ina388/

Also have one of these: https://www.seasucker.com/shop/mini-bomber/

The Seasucker works great on my wife's minivan and has done many week long trips. The Inno stays on my SUV and is great in that I can put bike up there with disc wheel on. That was a requirement for me.