Same shocks for coils and bags

[forestb]

I have a rear shock that needs to be replaced because it is leaking. In the future I want to install air bags. If or when I get bags the plan is to keep the ride height around the same. My question then is will one shock do the trick or do I need to get new shocks when I get bags? Also what is a good shock? I am looking for a comfortable ride more than high performance. But both would be grate.