People run The Pit for the obvious reason - as you said: alvl 85.
The difference with those areas - elites/champs and Act Bosses is: Act Bosses have a higher % chance to drop most items(within their Standard TC ofc and much better TC with higher level TZ) and generally drop multiple items - More items, more chances at a desirable item.
Overall - do what you enjoy or what’s easiest for you.
You can find comprehensive TC lists anywhere online.
If you’re running TZ’s I strongly suggest taking a look at this excellent post by Zax:
This is a very valuable resource if you’re into optimizing your TZ runs or merely curious about where your Character/TZ level lines up with various TC’s and what to expect.(He goes into detail about TCs in regards to TZ - def worth a read!)
Level 85 Area: While The Pit is great - I’ve fallen in love with The Stony Tomb.
Smaller, Semi-fixed maps, more density, more champs and elites, more objects/clickables, good chance to spawn Armor and Weapon racks etc.
If you haven’t seen it, here’s the list from the 2.4 Patch Notes.
Multiple areas were upgraded to Alvl 85. Stony Tomb being one of them.
Monster Levels in the following areas have been increased for Hell Difficulty:
Area
Previous Hell Level ~ New Hell Level
Act 1 – Underground Passage Level 2
83 85
Act 2 – Stony Tomb Level 1
78 85
Act 2 – Stony Tomb Level 2
79 85
Act 3 – Arachnid Lair
79 85
Act 3 – Swampy Pit Level 1
80 85
Act 3 – Swampy Pit Level 2
81 85
Act 3 – Swampy Pit Level 3
82 85
Act 3 – Disused Fane
84 85
Act 3 – Ruined Temple
84 85
Act 3 – Forgotten Reliquary
84 85
Act 3 – Sewer Levels 1
84 85
Act 5 – Abaddon
81 85
Act 5 – Pit of Acheron
82 85
Act 5 – Infernal Pit
83 85
Act 5 – Drifter Cavern
84 85
Act 5 – Icy Cellar
83 85