It depends. Generally, I prefer a low hydrogen SMAW electrode that's be properly stored or possibly GMAW or FCAW depending on the thickness and position.

If you are working to a specific code, review the requirements before jumping on the band wagon.

Al

As Al noted, your first consideration is your Job Specifications followed by any applicable code that may be invoked by either the Job Specs or customer PO/contract. 

From that also is the question as to the purpose of the overlaying/surfacing of the base material.  It may be that any Low Hydrogen electrode, FCAW, GMAW would be satisfactory though if the purpose is to build it up followed by a hard surfacing layer then some manufacturers also make special build up electrodes to handle the compression forces involved.  Follow that with the actual hard surfacing electrode.

Obviously this is speculation on my part as you did not give us many details.  But it seems pretty simple to just build up a worn part with 7018 or FCAW/GMAW if it isn't for special usage so not sure why you would have asked.  I do notice your tag line seems to indicate you may be an engineer so you may not totally be informed as to welding procedures.

I hope one or both of my scenarios is of assistance to you.

Have a Great Day,  Brent