I was one of those flaky players who disappeared in the middle of the game last time - Though there were circumstances that I would like to think permit that. Nonetheless, that was one of the biggest problems: People who didn't have time for the amount required. Especially for the paperwork. I'll throw my voice into the argument that it needs to be made simpler. Yes, a large-scale strategic exercise is a great idea, but in practice it can be very problematic (as we have seen). As some have mentioned, having one player per faction is a good idea, because teamwork, time committed, and having something to do (in comparison to the faction head) are all issues.
Therefore, it needs to contain the aspects that we've enjoyed in the past, but simplify! For example, instead of tracking every last 'Mech and fighter by force points and their movement, use a more abstract system. To extend the example a little more, let's say the Federated Suns have taken extensive damage in their last offensive. The player chooses the option to 'Focus on Mech Production', instead of 'Focus on Fighter Production' or 'Focus on Industrial Production'. This system could also work for other things, like officer training, economy, etc.
Overall, the point I mean to make is that if there are orders every week, it should take no more than twenty minutes to make. That includes decision time. It makes things easy. As we have discussed, unfortunately not everyone will be perfectly happy. But I feel this will keep the game open for everyone, including the casual players.
Those reasons are why I voted for Tech and Resource Advancements. Though, as I said, abstract is better that tedious detail.
I'm also in strong agreement with monbvol about MegaMek. Having matches is simply too tough for a huge game. A small roleplaying group could, but not with the number of players and how long we run these games. Therefore, I voted for the use of MegaMek to resolve duels/trials. As some have said, it only works well for Clan games, especially very political ones. We should not rule out entirely MegaMek, but keep it as an option for certain games.
Faction-wise, I'm happy with Clan or IS or anything! So, I'm content with whatever anyone wants. However, for ideas that intrigue me, I loved the entirely political RP FWL Parliament idea. Naturally, some players must have combat, but I really like this idea. In addition, any Clan ones are good. Especially ones that involve a single player per Clan, starting a year after Klondike or at the death of Nicholas or at the start of OmniMech technology. It keeps Trials small (not Reaving size!), has many rather equal Clans, has many personalities already established in Historical: Operation Klondike, is very political, and has lots of room for tech advancements.
Lastly, I indicated I would be willing to GM if necessary. As with lack of strong opinion on era, I'd just like to see a game started no matter how. However, with my schedule and lack of smartphone, I couldn't be a primary one, but if necessary, I can help out in this area.