I been trying high defence build (with standard WB masteries though - ID/SL/DW) last few days with 4-4.2k armor, 400~ toughness, occasionally switching jewelry between WI, genesis and parry stacking. It seems to work decently well but its been hard to find a decent 1v1, even when you find someone suddenly a healer or a roaming group pops up out of thin air
As for builds...
I feel like parry/riposte cheese is the best bet for solo roaming there is.
You have very little ways to deal with ranged enemies and to stick to them once you got close(snare lasts 5s while having 10s cd). So IMO its better to just don't bother about ranged enemies and gear up to kill melee.
Stoutness of Stone IMO should be considered mandatory because otherwise you get eaten for breakfast by first decently geared WE.
Parry is not a panacea though, when snared its pretty hard to keep enemy in parry window and i suspect part of that is due to latency issues. I had a few deaths where on my screen enemy would just get stuck on top of me, whereas on their screen they went around me and is hitting me in the back.
Rampage gives you better chances against other melee and tanks, but they also have tools of their own so its not like it is auto win. After all you still have to face armor which cuts quite a portion of your damage. Stacking high WS isnt as effective as people seem to think and comes at a price of losing defense, although less so when you are very high RR
Rampage is no more "broken" than having free 100% armor penetration, roots, disarms, knockbacks, pulls and so on.
Every class has something, compared to others Slayer has the least amount tools to work with, at least let us have Rampage.
RoA is also often heavily mitigated by armor and doesn't heal that much, i don't even use now.
Incapacitate IMO is weaker than what other classes have. It requires you to be in combat for 15+ seconds (if you use Rampage or Enervating blow add +5 seconds for each) and when you use it you lose damage bonus, while many other classes have KD on demand and can combo it with their burst rotation.
VS Ranged, slayer needs to be good to pull It off.
i see almost no ranged solo roamers when i play, only Magi but they dont count because they have tank-level defences
but i feel like against ranged opponents it just comes down to who has better proximity awarness - if you get a chance to engage them in melee you have a chance
I don't see how a slayer can be kited by a WE since Slayer has a charge and WE doesn't, but ok.
If the enemy pops Flee and you were ~50ft away from them you wont catch up even with Charge - true for any ranged enemy when they engage you first, as well as for SH/WE after self-punt or any tank who managed to land punt through your parry