Progressives for me. I've had them for over 20 years, and if there was an adjustment period it must have been incredibly short....I don't remember one at all. I'm at +2.25 diopter.
So a few people have touched on very good points. With progressives lenses, you get that intermediate focus for things like your DASHBOARD or computer screen. Sure, you may have to move your head around a bit to find the right spots, but eventually it comes natural.
You CAN'T do that with regular bifocals. Your vision is either right or wrong, there's a cutoff line, it's either on or off, no in-between.
If you start out with regular bifocals (with the line) it will make it MUCH more difficult to adjust to progressives. Don't make that mistake.
It is important to get good lenses, and not to go too small as others have pointed out. Mine are Varilux, with the Crizal coating system. This minimizes rearward reflections and helps with light transmission.
I also prefer the Men's metal frames with a rimless bottom edge. These typically allow for a bigger bifocal area and seem to work much better that a lower frame.
I regret that the Japanese company (Marchon, I think) quit making the FLEXON frame. This was flexible titanium/nickle alloy. A metal frame that you could twist into a knot without breaking! Incredible! I've had two pair that I now use for sunglass frames that are 40 YEARS OLD! No tarnish, nothing! No wonder they sold the name, but the new versions are not the same quality.