Bandwidth should not be the only consideration - also consider redundancy.
In a single switch environment, LACP will offer redundancy should one of your aggregated NIC's fail. Should this happen while doing manual load sharing then whichever service was bound to the failed NIC will also fail. This redundancy increases if you have multiple stacked switches and connect each LACP link to a different switch.
As for which method will provide more throughput, if I understand your scenario correctly, then link aggregation will only really increase throughput when multiple clients attempt to maximize their bandwidth with the server at the same time, whereas manual load sharing only really increases throughput when there are different clients using each service at the same time.
So which of these two scenarios do you think will be more common in your environment? And there's your answer.
(E.g. with LACP you could have 2 servers accessing an NFS share at 1Gbps each. Whereas with manual load sharing, you'll still only get 0.5Gbps per server, because they both must use the same physical link. But if you want to ensure that your NFS and SMB shares are both guaranteed at least 1Gbps each, then manual load sharing might be the way to go).