The Tread Switching Game

Power Treads. According to Dotabuff, they're not only the most common boot of choice in the game, rather, they're the number one most bought item in the entire game (even more the Town Portal Scroll)!

But, what if, for some reason, let's just say by means of a reborn glitch or Ice Frog nerfs the treads into oblivion as a result of a drunken stupor, you were unable to build these handy dandy boots?

For this game, you must think of a hero you almost always build Power Treads on and think up of another pair of boots to build on said hero and explain your choice.

I'll start us off with Shadow Fiend and my alternative boots of choice will have to be... Arcane Boots? Here's my reasoning, if you're like me, then you're liable to wiff on a couple of razes, to the point that a simple Bottle charge won't cover it. That's were these magical kicks come in! Giving you nearly two razes worth of mana! "But Fedo, a Bottle can do that too! Indeed, but can a Bottle give you 55 bonus move speed and an extra 250 mana to your mana pool? The answer is no. But I'm not done yet! Arcane Boots can build into the Guardian Greaves by combining it with a Mekansm and a piece of paper! And wouldn't you know that Shadow Fiend is already a known mek carrier, so it's a perfect fit!

Now then, let's play everybody. Let's. All. Play.

Easy : plain Boots of Speed on every hero, buy your early game items, and then grab Boots of Travel when you can afford them. I'd honestly do that on every core if treads are nerfed into oblivion. Travels are just the best boots in the game right now, by far.

Basically what Hamster said; Any hero who normally buys treads would buy travels in most cases, and if not you'd see Travels. Phase in specific situations.

Maaaaaybe in some really specific situations you'd see like SF and others picking up Arcane Boots to go into greaves.

Hamster be like

Treads on PA.

Phase is better.

EDIT: Oh, and DotAbuff only counts the items that you end the game with, that's why TP scroll isn't at the top.

Power Treads are way overbought to begin with. A lot of the "default buyers" are not very good with it.
Arcanes is better on Magnus. Tranquils/Arcanes are better on VS. Arcane/Phase/Travels are way better on Necro. ET is better with Tranquils/Arcane. Siren is better with Arcane/Travels. All of the three other boots are better on Venomancer.

The types of heroes that buy treads almost all the time are heroes that really need that cheap attack speed and stats for fighting and farming like Wraith King, Chaos Knight, Phantom Assassin, Faceless Void, Weaver, and Anti-Mage. Most lower position heroes go for the more useful boots, with exceptions being Support Silencer and Spirit Breaker.

Hamstercharmer is probably right that most of the carries that go for Treads usually will be going for travels. The movespeed granted by it is so much better relative to treads and the teleport lets you farm so much if you are given the space (to the point where I've been neglecting treads in favor of direct travels on both Dragon Knight and Outworld Devourer lately, but I do play them very greedily). With nerfed treads, the carries that fight early will likely switch to phase if it's useful for them, otherwise, they will take the slot penalty and go brown boots into travels and are a lot more likely to pick up some nice early fighting item like Drum of Endurance

However, this does leave a small set of heroes that may buy something else. Mids with a focus on ganking that need to make space for some really greedy carry, but generally go treads for extra right click and for treads swapping. Heroes like Queen of Pain, Puck, Storm Spirit, mid Silencer. Since these heroes are all INT heroes, many of them can go the path of Arcane Boots disassembled later into an Octarine Core, but they will still get that travels later. Maybe we'll see things like Phase Puck be a thing.