I use an Optima and a Viso, both by L&B and I would highly recomend them. The guide mode on the Optime (series of beeps getting faster and faster until your landing turn altitude) and the +/- 10ft accuracy on the Viso were incredibly helpful when refining my setup.
With the viso you are able to see max vertical speed under canopy. Cool
I can see my profile with Neptune.
This is my favorite so far. I just started 270's and ran into a minor problem. My death siren goes off on my dytter when I'm landing now, and my Neptune goes back into freefall mode sometimes .