In my limited experience, many people seem to have strong feelings about certain rulesets. However, the nice thing about historical wargames in that (basing specifics aside!) you can generally use them with lots of different rulesets.
I would therefore *strongly* suggest getting something more modest as an initial starter force for each side, and try playing some games with them first.
To guide you, I would probably pick a period/theatre of the war that interests you, and begin with a smaller number of suitable models.
For example, let's say you were interested in the North Africa theatre, and wanted to field some German forces against the British. I would then start with a couple of boxes of plastic troops for each side, along with a couple of trucks, a couple of half tracks, and maybe a light tank each. There should be enough stuff in the infantry boxes to make some command models with, and also a selection of support weapons. The only thing I might add is a single weapons sprue (if you're buying direct from Warlord, or from ebay) to provide any small arms you may want but which aren't in the troops boxes.
If after a few games you find that Bolt Action isn't to your liking, or that a different force/theatre has taken your fancy, at least you're not so deep in that you feel you can't swap or give a different ruleset a go.
With BA specifically, it was always designed to be based on a game size of about one platoon plus some support elements. Obviously, bigger and smaller games are possible, and many supplements have been released since; but at it's heart, this is the size of game where the rules generally work best. And at this game size, whilst having some options to choose from in your forces is of course nice, you'll probably get more variety from the games if you change up the terrain setups and scenarios instead (and that potentially doesn't require more money/time/painting!).
Based on this comment:
As I am reading and watching more and more about the game [...]
It seems fairly probable that you have watched Tabletop CP on YouTube - as well as Bolt Action, the guys there also do Chain of Command (another WW2 platoon-level ruleset), and even back-to-back games with similar forces and terrain but using different rulesets to show how they can differ. I mostly mention them, as their forces are reasonably typical of what many players might field, and they do also use the same models across the various different games they play.