Radar increase and icon range decrease would be my picks
Eagler
By "radar increase" I assume you mean every plane in the air over 200 feet has an icon on the map no matter if a friendly is close or not? There goes the "fog of war". Sure "fighter guys" think that would be awesome, but the vast majority of players we have even today are in the game for the "war" aspect of the game. Hitech setup a game for pure fighter (War online: Pacific ) and it never took off. MNM gets what 10-15 players on a good night, that is a small percentage of players of the game. No not EVERYONE wants to do fighters and if the changes made to this game turn that way it would close down the place in a couple of weeks.
I think the radar as it is causes problems too. Im sure MOST players hate getting shot down by some degree or another. when a player is climbing out on an attach run and a fight icon pops up he has to make a choice. If he dislikes getting shot down only a little bit he might try making his run anyway. What follows is either he dumps his ords and a fight ensues, he kamikaze's in on his target dieing there, or gets picked trying to dive in on his target. Or if he hate dying alot, he just turns away from the icon and runs.....all the way home if necessary.
Todays players dont spend the time playing this game and learning it like us old foggies did. There are too many options for them and they use them. That lack of time in game means these players have very little confidence in their abilities to win a 1 vs 1 let alone diving into gangs. Take away their "hiding" spot by wiping out radar and they will most likely leave to those other options. I wish Lusche would have another kids so he could stay home and make a comparision of the average player 10 years ago vs the average player of today.
Messing with the icon ranges is one of the things that killed AvsA arena. For away they were getting decent numbers (the whole game had decent numbers back them) but a group of players thought it would be cool to make it more realistic by changing the icon ranges which lead to complains to players just not showing up any more.
The only thing that is going to bring the game back to the glory days is better numbers. Twice the numbers means that there is twice as many fighter guys, twice as many win the war guys, twice as many gvers and so on. That means half as much trouble finding the type of fight/play you want out of the game.
That means the graphics, subscription rates, ENY setting, user interface all has to be updated to match closer to what is out there now. To those of us who play these things are fine for the most part, but we all know the ways around things and the fights are more important than how pretty the plane is that your HOin.

To a new player it is something pretty important, after all there are so many other choices out there.
Any changes to the game now as far as "tweaks" have to be thought out very carefully as the balance we have now could drop out and we really arent that far from the bottom as it is.