erectus and reidi are both super hardy and are fine for beginners.
the real question is whether or not you think you'll want to try breeding them. erectus give birth to fewer, larger, benthic fry (benthic = they can hitch at birth). reidi give birth to large broods of smaller, pelagic fry (they don't hitch for a few weeks) that often require smaller first food (rotifers).
of course, if you don't want fry at all, you can keep a "same sex" tank with no issues.
DanU (SH source) has great stock and is really great. Beth (Peka here on RC) has some of the most gorgeous erectus i've seen. i highly recommend them as your possible sources.