I usually prefer '33 for the same reason as above, because I tend to like asking myself questions like: "What if South Africa militarized after the Acts of Dominion and staged an invasion into Brazil?" As such it's not so easy to shoehorn those into the '39 scenario
I think a lot of people like that scenario because they can start with a clean slate too. build what you need so when '39 comes around you have
your fleet,
your army, and
your production line. It's a bit daunting to look through a 100 Russian named divisions when you start '42 trying to figure out what the hell's going on.
I usually try to play non-gamey tactics, so no destroyer zergswarm, no subswarm, and no naval bomber swarm, and I usually try to give fair part and parcel to all parts of the military.
Ay, the bloody subswarm. In the MP games I've played we also had cultural rules. So Japan could not send 20 divisions to go fight for the Entente in North Africa in 1916.
I also have a weak spot for shunning carriers fleets. It's been my experience that a destroyer+AA screen-heavy SAG can usually compete with a CVBG if they aren't just dominant tech-wise.
The '14 scenario can be fun to make those things less complicated. small air force, and the fleets are just battleship action, the bigger the guns and ships, the better.
As for the technical side of things, the last time I used Hamachi was like almost a decade ago, and I've never used gameranger. However, they're both just simplified VPN solutions. It should be possible, in, theory, to just set up a VPN e.g. to someone's house network. But I don't know if Hamachi/Gameranger have some sort of secret sauce to make their programs better than plain VPN.
I think people use Hamachi/Gameranger because it's easy. Not sure how you could set up a DH game through Steam. I mean you could set up a Steam DH game through Gameranger. But it's easier to have the lobby chat there and do last minute rule changes. For me it's whatever, as long as the connection is stabile, and no one has a hard time figuring out how to connect to the game.
I figure the best way to run a game is to do once a week sessions for a game that would last IRL about 6 months (maybe a year if the game got intense and the players were great). That would mean a couple of months in-game every session, the sessions would last IRL a few hours, maybe like 3, 4. Then you would have a forum that's open 24/7 where people could post in a general thread for world diplomacy, rules, banter, session dates, etc. Then 1 locked for the Axis, and 1 locked for the Allies, where maps could be uploaded, and strategy could be devised between the nations.
If you started at '33 the speed would of course be pretty high until war looms.