15 or higher solo on the tier 3 and 4 maps is pretty good.  Wave 17-19 will get you top 10,000 on the leaderboards on a bunch of those maps (xbox). 

For the standard maps I think top 10,000 is worth bragging about.

For the DLC maps I think top 2000 is about the equivalent.

Wave 36 Solo Village. Was Rank 11 at the time but since dropped due to all the hackers.

Map: Piazza

Co-op:52

42? Dag, teach me how to play.

Seatown: lvl 25 Solo

Seatown: lvl 31 Co-op

So not so good at survival...

Players: 2

Map: Resistance

Wave: 38