Old Man Emu has been the dominant supplier of suspension for Land Rover for a very, very long time. They're an Australian company that was bought out by ARB. You can not go wrong with OME. They make a good variety of spring rates for your application, and the shocks are double-wall steel construction, nitrogen charged beasties that will stand up to a lot of abuse. If speed is a factor, check out OME's LTR shocks. They've got you covered.
Bilstein also make a great number of high quality shocks. The factory-spec replacement jobbies are high quality and valved well to a light-to-medium use trail rig that sees a lot of pavement. They will not soak up 50 miles of desert road at medium speeds carrying a load like an OME shock can. It's just beyond the design specs for that shock. To compete with an OME shock with loads and heavy use, you need to look to the 5100 series chocks from Bilstein. The problem is, getting the valving right for your specific truck can take some experimentation, and you'll have to convert the mounts from posts to eyes on your shock mounts using adapters, which requires a careful study of shock length and the final length eye-to-eye after conversion. After the 5100's, the 7100 series are a racing shock and fully rebuildable and have support for total custom valving. Unfortunately, they are HEIM jointed shocks and, in my opinion, constitute a poor choice for an overlanding rig, due strictly to the service life of HEIM joints compared to regular rubber bushings.
Ymmv.
cheers
-ike