Given that the new playtest UA messed with the behavior of 2 formerly Ranger-only spells that are intended to now be released to Druids, Hunter's Mark and Conjure Barrage, I've decided to try my hand at something similar: buffing these spells when cast by a Ranger.  Feedback welcome.  I'll be including the UA's version of both spells, but I'll be modifying Conjure Barrage more extensively.

1. L1 spells are modified when cast by an L1+ Ranger.
   
   • Hunter's Mark: No longer requires concentration and can be dismissed as a bonus action.
   • Ensnaring Strike:  No longer requires concentration, can be dismissed as a bonus action, and can be cast after you hit and roll damage with a weapon attack.
   • Hail of Thorns: Instead of requiring concentration, this can be cast after you hit and roll damage with a ranged weapon attack; change the duration to instantaneous.
   • Zephyr Strike:  No longer requires concentration, can be dismissed as a bonus action, and can be upcast to a maximum spell level of 5, which increases the force damage to 1d8 per spell level. 
2. L2 spells are modified when cast by an L5+ Ranger.
   • Cordon of Arrows:  This can be down-cast to level 1, which reduces the number of pieces of ammunition to 2.
3. L3 spells are modified when cast by an L9+ Ranger.
   • Conjure Barrage:  This can be down-cast or up-cast, to a maximum spell level of 5.  It deals 1d8 damage per spell level.
   • Lightning Arrow:  Instead of requiring concentration, this can be cast as a bonus action during a ranged weapon attack (after the hit roll but before the damage roll, if you have a damage roll to make); change the duration to instantaneous.  This can be down-cast; the target takes (SL+1)d8 lightning damage, and then creatures within 10' roll against (SL-1)d8 lightning damage, where SL is spell level.  At SL 1, this is 0, so there is no save to be rolled (much like how Booming Blade doesn't deal damage on hit until scaled).
4. There are no L4 Ranger-only spells.
5. L5 spells are modified when cast by an L17+ Ranger.
   1. Conjure Volley:  This can be down-cast.  It deals (SL+3)d8 damage.
   2. Swift Quiver:  No longer requires concentration, can be dismissed as a bonus action, and can be down-cast.  In order to give it a sane down-cast, it first has to be brought up to par with similar spells (it's always been worse than Spiritual Weapon for its spell level, it's just that that's obfuscated by Spiritual Weapon's weird scaling - remember, 5E is designed such that a scaled up spell is intended to be worse than a spell at the scaled spell level, so a scaled down spell should be better than its peers, and we should concern ourselves with other spells that serve a similar purpose, like Haste), so the SL 5 version below is a deliberate upgrade to Swift Quiver:
      1. At SL 1, Swift Quiver works like it does now, but it only provides 1 bonus action attack (in an 3-round combat, it provides 2 attacks).
      2. At SL 2, Swift Quiver is similar to Spiritual Weapon: you can make 1 bonus action attack when you cast and 1 each turn during the spell (in a 3-round combat, it provides 3 attacks).
      3. At SL 3, Swift Quiver works like it does now (in a 3-round combat, it provides 4 attacks).
      4. At SL 4, Swift Quiver lets you make 1 bonus action attack when you cast it, and 2 bonus action attacks on subsequent urns (in a 3-round combat, it provides 5 attacks)
      5. At SL 5, Swift Quiver works like Spiritual Weapon but with its current attack count: you can make 2 bonus action attacks when you cast it and 2 bonus action attacks on subsequent turns (in a 3-round combat, it provides 6 attacks).

On a similar note  we need clear wording about cordon of arrows and swift quiver using poison ammunition. 

Different people have different opinions on how it affects their "power"/usefulness but at the very least it needs to not be misunderstood.