To add to what ABM said NMZ is still the fastest method given the use of overloads, I would definitely train via Slayer unless you’re just going to use the account to stake otherwise you will just find yourself doing post 99xp for no reason.
If you are in a clan, just have lots of friends or alt accounts you can use the house spec restoration pool to chuck dragon claws to other people in your house for mad combat xp/h. But in all seriousness go to nmz and pick some bosses which gives extra combat xp (moss giant, dad etc..)