If it's just me, dry and I wear my headphones half off so I can hear my voice acoustically.
I found very few vocalists who need reverb while tracking. It comes down to what they are used to hearing. If they have done lots of studio work they will be fussy about the mix more then the reverb. Some singers like a sparse mix with mostly piano to keep pitch. To add reverb I always monitor though a mixer so both of mine have lots of presets I can use. My system has too much round trip latency to use Sonars plug ins anyhow, unless you like a 24ms slap echo.
There's a danger in sweetening up the singers voice to much while tracking as it can tend to gloss over minor mistakes. But sometimes the efx is part of the song so that is different. In that case I'd record 2 tracks simultaneously, one dry and one wet.