I think Tippmanns are the clear winner. They are the industry standard rental, they last for ever, and they are cheap and plentiful. I think you would be hard pressed to find a player that has not shot someone out with a Tippmann. They may not be the best markers, but they are by far the most common (on a field).
Cattle die, kinsmen die
all men are mortal.
Words of praise, will never perish
nor a noble name.
- The Havamal