In terms of avionics and flight realism with the capability of full blown dynamic warfare, Falcon 4.0 with FF5 installed simply is the creme de la crop as it were.
No game even comes *close* to it. However, all of that realism comes at a cost of a learning curve that more or less resembles the cliffs in acapulco.
Even the most die hard sim freak has an issue or 2 with it, and EVERYONE takes a long while to learn it from the ground up.
It pays off in dividends once you know how, in gameplay. The thrill of a fully dynamic war happening around you is just unrivaled.
In FF4 (red viper), I was in an F-15 strike eagle sent out to destroy a bridge before the enemy got there. Being the oppurtunist that i am, I loaded down with 6 (or eight? can't remember) CEM cluster bombs- just in case
While I was in flight, the enemy got there, and there was a vicious arty barrage givin' our boys hell. The battle for the bridge was in full pitch.
First thing first- take out the bridge- 2 GBU-24's and it's history. Switch to the CEM's, toggle CCIP, 1 pair a pickle, split S, and light the cans. Screaming power dive to hit those damned guns.
Dropped all of my CEM's in one smooth CCIP pass, and DECIMATED the enemy arty and troops. Kill list was as long as my arm. Someone then called for a bit of help with some a/c attacking our boys, so I ignored my mission directives to RTB immediately, and went gunnin for a pair of Frogfoots.
2 AIM 120's and about a metric ton of fuel later (

), I had 2 frogfoot pelts to my credit.
RTB to good ratings, but a very curious commanding officer...as to what I was doing CAS work in an F-15E.
Gawd, now I wanna play s'more. Damn you!!!
---LOMAC---
Lomac is by FAR the more playable of the 2. Learning curve is not nearly as steep (still vertical for first time jet simmers, more like a bunny hill for us types)- a few minutes in your a/c of choice's tutorials and you can do all right in it.
Where LOMAC's strength lies is in it's mission builder. They're canned missions, but they can be a LOT of fun.
LOVE flying my Eagle in there
Basically, if I have about a 1/2 hour to goof around, I fly LOMAC. If I have an entire afternoon off (wife-ack relocated

), it's Falcon.