I used both..  Can tell u the pros and cons :-

Nexus 5
1) very smooth os because it always gets the latest update
2) pure google experience
3) slimmer profile due to 4.95in screen
4) standard comes with 16gb

G2
1) currently kitkat 4.4.2 however rom not as smooth as n5
2) 13mp with ois is superior to n5 in any conditions
3) larger screen 5.2in
4) 32GB
5) 3000ma battery vs 2300ma longer battery life by almost 40%

Price of both not much difference only rm150 more for g2.