The P14 is significantly more robust than a Lee Enfield dude. It's basically a mauser action, which due to front locking lugs, can handle much higher pressures than any rear locking rifle. That's why P14/P17 actions are often donors for massive cartridges like that .577 abomination of a round. Also, parts break much less than a Lee, which often have problems with bolt heads. If you don't believe it, check out why the P14 was made (hint, it was made to replace the Lee Enfield, and was in its original guise supposed to chamber .276 British, which is only a little bit less potent than a 7mm RM, which is incredible for a round developed in 1913). In no way, shape, or form, is a Lee Enfield tougher or more reliable than a P14. Lee's do however, take a 10 round mag, which is pretty sweet. You will find that people here have a soft spots for Lee's and they are certainly good guns, but from a military, and objective standpoint, the P14 is a better rifle. That's not to dismiss the Lee Enfield, but there's a reason Mauser actions are what essentially all modern bolt guns (and most past military rifles) are based around.
Ross Rifles are not rifles made for war, in my opinion. Too finicky and sensitive for a bolt action rifle.
EDIT: P14's were made in the US by 3 companies; Winchester, Remington, and Eddystone Remington Arms (a plant made by Remington, to solely produce P14's). They were sold to the British, who used them as Home Guard rifles, to ensure they only had Lee Enfield No. 1 Mk. III's on the front (to simplify parts for armorers). When the US entered the war, they needed more rifles, because the Springfield 1903 was too hard to tool up for again to issue to the AEF, and because they were having problems with heat treatment for the 1903's recievers. The rifle they went with was a P14 converted to .30-06, with the volley sights removed, and the "wide belly" of the P14 removed, in what was issued as the M1917 rifle, or the P17 as many call it. So it's ironic, the British rifle, with a few tweeks, saw more service with the Americans than it did with the British. The Americans were making 10 000 P17's A DAY in 1918.
It's also considered by General Julian Hatcher, to be the best rifle of WWI