Well, it really depends on your intentions - do you think you want a 7-string for lower tunings down to B or A standard? If so, maybe a Baritone guitar is better. if you want to go even lower, you'll need a Baritone with thicker strings, or perhaps even a 6-string bass is better.
But if you want to maintain access to the high notes found on a normal 6-string guitar at the 22nd/24th fret, then you need a 7-string guitar (or an 8-string if you want even lower bottom end).
A 7-string is also a good idea if you don't like the extended-length neck of a typical baritone guitar.
OTOH, the wider neck of a 7-string can throw you off (worse on a 8-string).
And yes, a Digitech Drop or similar is a relatively cheap way to explore drop tunings, although, like any device that pitch-shifts, there is going to be tracking miscues, latency, and issues with chords. The Drop is pretty good, from what I understand, though.
There, does that help? :flute: