One lvl 50, or two lvl 46s?

Specifically asking this about PVE not PVP. For non-shadow Legendary / UB pokemon, it costs 296 xl candy to max out at level 50. If you are FTP or just not spending lots of money, this can be quite daunting. Even with the 3 bonus xl candy for local raids and using a maxed mega level 3 and mirror trading (when seasonably appropriate) Thats an average of 8 XL candy per raid. So at ~37 raids for one level 50 pokemon, you want to make your investment count. With 296 xl candy you could make one lvl 50 pokemon, or spend 148 xl candy on two pokemon making them both level 46. Despite focusing mostly on PVE for many years now, I always find myself asking this question: should I max out one or should I have two at a very high level? Think Dawn Wings necrozma, or Palkia with SR, I know there's probably not a universal answer but what judgment criteria do you employ?