There's dozens of programs to try, use the one you're most comfortable with.
Features useful to others may not be useful for you and vice versa.
HRD/DM780 is cool because of CAT control and the EQSL logging, as stated.
It also copies weak signals very well, IMHO.
But I will always have a soft spot in my heart for Digipan,
the first really user friendly (click to tune) PSK-31 software.
Digipan made PSK-31 literally explode onto the ham scene, and turned an obscure
but spiffy mode into the biggest revolution in ham modes since SSB.
It's the software I used to make my first PSK31 contact
and the first PSK contact with a rig I built myself (Dave Benson's PSK-20 kit).
I remember first using it on slow machines running Windows 3.1.
Of course, a couple dozen revisions later it won't....but
I still have it on a 3.5" floppy around here somewhere.