Should I be looking for high sensitivity speakers or lower?

I have an 80 wpc amp and am thinking of replacing my speakers.

I had read that sensitivity is often compromised in higher end speakers
because higher end amps are often high wpc so can still drive them.
Although this sounds plausable I've also read that valve amps are ofter
low wpc. Besides dont amps prefer less work so they have more power in
reserve for fast transients?