Valla is a good example, with the exception of Caltrops. I still don’t think it’s good even after the buffs, simply because it doesn’t have synergies with anything, in particular at level 7 where taking Death Dealer is an anti-synergy while taking Repeating Arrow means you skipped Monster Hunter at one which is a pretty big no-no.
Why Valla’s tree is good: It has three clear build paths: Q build, Trait/AA build and W build. All of these have at least 3 talents tied to them with possible deviations at the other tiers that still synergise.
For example level 13 for Q build where Siphoning arrow competes with Gloom which is always a good choice.
Or level 16 where both Seething Hatred and Frost Shot are amazing additions to W build.
What is better than having 3 clear build options? Hanzo’s tree that provides three options that are all customisable.
Hanzo also builds Q, W or AA, just like Valla, but unlike Valla, ALL his level 7 and 13 talents boost two possible builds.
The Dragon Hungers (7) and Piercing Arrows (16) affect both Q and W.
Never Outmatched (7) and Giant Slayer (16) affect both AA and W. Note: With Never outmatched you can pick both Simple Geometry (more difficult but safer) and Redemption (easier but less value if you die).
Finally, Sharpened Arrowheads (7) and Flawless Technique (16) affect both AA and Q. In fact, Sharpened affects all 3 builds, but if you want W build, you probably want Never Outmatched.
Then his 4 and 13 tiers are waveclear and utility respectively, but in such a way that they are highly situational. (Except for Ignore all Distractions and Mounted Archery, they’re crap don’t pick them).
And finally, what is better than having 3 viable builds with deviations on multiple tiers? Sylvanas’ tree that does much of the same but literally all her talents are viable.
Sylvanas has a Q build, a W build and a trait/AA build as well.
At level one Might of the Banshee Queen boost all 3 with Unfurling Shadow affecting W build (recommended in longer games/on maps where teams get clumped a lot) or Overwhelming Affliction (paired with a Jaina/Arthas/Reghar/Blaze/etc especially).
Level 4 is waveclear/camp clear except this time all 3 options have their place.
Level 7 sees Barbed Shot as more of a Q build niche for maps such as BoE or maps with bosses. Festering Wounds is there for all builds, since all get bonuses from maximum trait stacks and Lost Soul is great for both AA and W.
All her 13 talents add value to all her builds. Period. Armor reduction, Increased mobility (with more Q’s AND the synergy with Festering Wounds), or more range and applying stacks to two (or more) heroes are all amazing. You literally cannot misclick on this tier (even if Windrunner pulls slightly ahead).
16 is survivability in the forms of sustain, speed or unstoppable. Again, you literally cannot misclick here.
Seeing how Sylvanas is also very much a generalist/hybrid hero with both Burst and Sustained damage, both Physical and Spell damage, I think she is certainly a strong contender for the best talent tree of the game.
EDIT: I chose these three Ranged Assassins because they largely do the same thing (hybrid damage) and can be easily compared to each other. Besides these three, here are other heroes that I think have decent to solid talent trees: Pretty much all tanks other than Garrosh (I’m also not sure about Muradin, Tyrael and Cho as I don’t play them), Cassia, Falstad, Zul’jin, Alexstrasza (with E build being on the weaker side), Rehgar, Uther.
I’m sure there’s more but I either don’t play them or I’d have to double check and look through their talents.