Help me choose what I want.

What a tangent! Just kidding, no offense.

I suggest you check out my useful links; you can find a lot of interesting things there.
And in general, the versions that are popular now:
4.0 complete (Platinum Edition):
Combines RoE, AB, and SoD; compatible with SoD 3.2 and is the most widely used on this portal.
SoD (The Shadow of Death) 3.2:
Patch 3.2 allows you to play with Platinum Edition users and fixes all bugs (glitches that dishonest people could exploit).
WoG 3.58f (In the Wake of Gods):
An unofficial patch (starting from 3.5), currently the latest. It has many enhancements, but it's not quite Heroes 3 anymore (in my opinion). It's not very popular, but it's necessary when installing TE.
TE 1.03q (Tournament Edition):
This is almost SoD, but the interface has been significantly improved, making life much easier for online players. But (again, in my opinion), the game's balance has been altered, and many things are not in their proper place, and I don't like it.
But there are still quite a few people playing on TE.

You don't even need to look at the other versions (AB, RoE, WoG 3.51 - 3.57, SoD 3.0 and 3.1) - it's almost impossible to find partners for them.
These are all the main versions of Heroes.
From an economic point of view, it's best to have the SoD disc, as you can create almost everything from it.
From a comfort point of view, 4.0 is the best - Russian text in the chat, you can see the amount of mana your opponent has in battle (which you can't do in SoD), and there are a few other minor improvements....