squirtdad

my 2 cents, worth just about that

I use all spd, spd-sl clipless and to a much lesser amount clips and straps.

I find the common advantage to all 3 is that my food is positioned correctly on the pedal and no energy is spent adjusting position

IMHO the shoe you are wearing makes more difference that the clip or clipless systems, you get more efficiency from a stiff sole than a soft tennis shoe

I like clipless, it is for me, convenient, use use clip on my Cino/ Eroica bike

I use spd for commuting, as it is the easiest to get in and out of multiple times

I use spd-sl for long rides, training (I tell my self it is training) as it feels more efficient and spreads pressure out