Few globular clusters have any information of number of stars or the total masses. Most are frankly guesstimates, but some of the largest or closest can be roughly estimated. From the 13 billion ages of these beasties, the initial stars forming globulars have long since gone, leaving the largest stars at about 0.8 solar masses or less. This mass can be estimated from the so-called turn-off point - the place on the globular's H-R diagram. It also tells something the the cluster's age. From this a distribution can be calculated. The following list gives a rough range in mass and number of stars.
NGC 6388 in Scorpius is by far the heaviest by far, while
Omega Centauri and
47 Tuc are close behind.
Top 3 by Mass and Number
NGC 6388 (Sco)
M⊙= 2 510 000 No. Stars= 3 500 000
NGC 5139 / ω Cen
M⊙ = 1 440 000 No. Stars= 2 000 000
NGC 104 / 47 Tuc
M⊙ = 150 000 No. Stars= 1 600 000
Smallest Clusters
Pal 5 (Ser)
M⊙ = 23 700 No. Stars= c.70 000
NGC 6366 (Oph)
M⊙ = 15 500 No. Stars= c.40 000
Pal 13 (Peg)
M⊙ = 1 230 No. Stars= c.25 000
On any true scale they roughly average up to about 50 parsecs or 150 light years across producing about one star per light year or 0.25+/-0.10pc.
Maximum densities could be as high as 1 000 stars per parsec! 
According to the data derived by
Cheroff and Diorgovski;
AJ.,
339, pg.904-918 (1989), in real terms,
NGC 5854 in Hydra is the most tightly packed. Second is the core of
47 Tucanae, while
ω Centauri comes in at a surprisingly low 15th. One of the least compact globulars we presently know of is
Pal 15.
I can give you more technical details, if so required, especially if you have some cluster in mind.
