Many banjoists (and players of other stringed instruments) complain about all kind of problems with tuning pegs compared to geared tuners. Two of these problems are real: a tuning peg requires a sensitive hand, since minor adjustments result in relatively large pitch changes, and they do require a bit more mainteneance than modern high quality geared tuners. All other problems are due to sloppy mainteneance and should be blamed on the owner rather than the pegs.

Geared tuners

Geared tuners, or machine heads, have been around at least since the 19th Century but didn't really become common on banjos until well into the second half of the 20th Century. As the name implies they have a built-in gearing mechanism that reduces the turning-to-pitch change ratio simplifying minor pitch adjustments. There are three basic tuner designs:

Planetary tuners - everything's in a straight line, resembling the look of a traditional tuning peg as closely as possible.
Offset tuners
Guitar style tuners - with the "ears" sticking out from the edge of the peghead; ugly, but cheap and effective.

Virtually all banjos made today have geared tuners for obvious - and good - reasons.

"Programable" tuners

No, there's nothing digital about this, just good old mechanics. In the 1960s Dan Bump and ace bluegrass banjoist Bill Keith invented a tuner that allows you to switch quikcly and securely between two different pitches for a string. Their idea has been copied by many other companies.

What to choose

For a modern banjo, originally fitted with geared tuners, the choice is simple: keep the tuners - or replace them with higher guality geared tuners if you're not satisfied.

For an old banjo with tuning pegs it's a bit more difficult. The current trend seems to be to replace pegs with geared tuners no matter what, but that's not always a good idea because:

There isn't nearly as much difference as most people think.
Comparing the old tuning pegs of banjo that's been hidden in an attic for fifty years or more with brand new geared tuners simply isn't fair. Any mechanism, even one as simple as a tuning peg, needs an overhaul after decades of neglect. Properly adjusted, cleaned and lubricated tuning pegs turn just as smooth as any geared tuners, do not slip and keeps the pitch at least as well as high quality modern tuners (and far better than cheap modern ones).
Changing might unbalance the banjo.
Geared tuners don't weigh much, but still more than tuning pegs. This extra weight added to the peghead can sometimes reduce playing comfort significantly. This isn't an issue for modern banjos simply because they're designed with geared tuners from the start.
Modifying a vintage instrument reduces it's future value.
All geared machine heads I've seen require larger holes in the peghead than tuning pegs, so you'll have to redrill to fit them. Right now it seems most banjo collectors have little concern for the "originality" of their collection. As long as there's one part left from the original pre-war banjo it's OK. This is bound to change sooner or later though.
Even so it's important not to be fanatic about this though. The collector's value must always be weighed against the practical use. It's also a question how "original" the banjo in question is to begin with. If it's a five-string banjo from the 1920s-1950s for example, there's hardly any chance the neck and the peghead are original anyway - no matter what the owner might claim.

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