An elegant triplet of fonts

I use the following set of fonts.

An elegant triplet of fonts that go together
Type Font
Sans Serif PT Sans
Serif Gentium Book Plus
Monospace Courier or Courier Prime or Monaco

Uppercase i v/s lowercase l in sans-serif fonts

Many sans serif fonts fail to distinguish between uppercase I and lowercase l. Twitter's new font is an example of this.

On top of that, Twitter started dishing out blue ticks on subscriptions.

These two features combine to form deceptive Twitter usernames, as demonstrated in this tweet by Adrian Roselli.

Some famous fonts like Helvetica and Roboto fail at it.

Helvetica has identical looking uppercase I and lowercase l.
Roboto has identical looking uppercase I and lowercase l.

But PT Sans passes this AppleTVPlus test.

PT Sans distinguishes between uppercase I and lowercase l by putting a tail on l.