As a working pro, my go to in outdoor portraits is a flash... Strobe ideally but flash if not. Here's my methodology... If using a reflector, you can use a white reflector, but you must have it close in proximity to see any sizeable difference, which eliminates wide angle or scenic shots but good for head shots. For any full body shots, you almost need to use the silver or gold reflectors and the distance they would be from the subject and intensity of light is very unsettling and uncomfortable for the subject leading to squinting and tears... Even the bouncing reflector technique (moving the reflector off of subject and bounce it onto subject, take the shot and get it off, or even closing your eyes, open, snap, close...It just doesn't work and isn't flattering). If you have large diffuser screens and add reflectors around the diffusers, as in a sports illustrated swimsuit shot, they are a full set up situation with multiple assistants and preplanned.
Flash allows me to skirt around all these issues... Of course, ETTL will never work for outdoor photos... You must shoot manual, ideally full power if your flash is more than 10 feet away, unless you are shooting 2.8 or faster. Also, for shoe mount flashes, you can go to almost any camera shop that's worth their weight and ask for a filter sample pack (tiffen and some of the bigger filter manufacturers have them) and these sample packs are cut almost perfectly for your flash, so if you want a sun gel, effect filter, et al, a little bit of tape to secure and they work wonders, and many of the time these sample packs are free, so even better. As far as strobes, there are low cost filter packs that can be clipped to flashes for effect/sunsets... so for me they give me the most amount of customization and intensity of fill, or if needed overpowering the sun, it's the most comfortable for the client, and in many situations, i dont need an assistant, whereas you usually need one for a reflector.
