Inline or one armed load balancer?

Ho do you usually add a load balancer to your network?

1. One armed mode and NAT everything
2. Inline Mode where you have interfaces in every subnet you have servers
3. Something in between where you have "outside" and inside" but maybe routing in the inside too?

First option is probably the easies to configure routing wise as you only have one default route, but you'd have to NAT everything on the LB and lose the source IP address visibility? Unless you add extra HTTP headers for example.

Second option would also be quite easy configure routing wise if you have interfaces in every server network on the "inside" and then just a default to the outside.

I'm wodering because we've ended up with setup where we have few interfaces and then lot's of static routes pointing all over the place. I guess it started as something like "internet on the outside, lan in the inside" kind of thing until someone wanted to access the hostname that was on the outside network and then we added few routes there and few NATs there...

Thanks for any ideas!