Treantmonk has a new video series on fixing the 2024 Ranger which, to be clear, I am enjoying. I don't agree with a lot of the changes, but I respect the thought put into them and think that some of his suggestions are very good.
His Hunter's Mark spell, however, is very bad. Here it is:
You can find the original source
here.
So why is it bad? Because it isn't a fix for the Ranger. It is a buff for everyone, and the Ranger suffers for it.
One of Treantmonk's main criticisms of the Ranger is that it lacks a clear identity, and he makes some changes to rectify it. One of the ways he does this is to make the Ranger spells more powerful, the problem is that Hunter's Mark doesn't just belong to the Ranger. Unfortunately, WotC decided to also give it to the Vengence Paladin, one of the strongest class/subclass combos in the game, as one of their automatic spells (this was a terrible thing to do, but it was done back in 2014, so there is probably no fixing it). They also made it available to ANYONE that takes the Fey Touched feat. This means that your Vengence Paladin, Eldritch Knight Fighter, Pact of the Blade Warlock, Valor Bard, Bladesinger Wizard, etc., etc. can take the Fey Touched feat and then spend at 3rd level spell slot to get +1d6 to every attack for the next 8 hours CONCENTRATION FREE! Yay?
I understand the problem with requiring Concentration on Hunter's Mark, but the correct place to fix this is in the Ranger class features (and probably a pretty high level feature). Not in the spell that just anyone can take and get the benefit of.