Still taking my time through Tesla Effect, so this is a ranking based on where I'm at right now (Day 8, Tesla Labs... yes, I'm going that slow. I'm trying to savor it just in case it's another 16 years!).
1. Pandora Directive
--- To me they took what they learned in UAKM, perfected it with this game, and upped the ante by providing multiple paths. Fantastic gameplay, storyline, and performances! Here's how much I loved this game: When I played The Matrix Online I ran a guild called The Enigma Directive and I was captain of the hovercraft called Pandora.

2. Tesla Effect
--- It's tough for me to rank this above UAKM because I still haven't finished it and UAKM is such a classic. However, I think the way the long hiatus between games has been handled has been fantastic and woven perfectly into the storyline. The gameplay has been great and this is pretty darned closed to the way I've always wanted to see Chandler Ave.
3. Under a Killing Moon
--- It's hard for me to mark UAKM as #3 when I've had some of the old midi music as part of my playlist for years, but it pulls up a little short based on a few technical glitches (can't complete torn note puzzle), some of the chessiness was a little too cheesy, and the worst acting of the the entire series is found here (Sylvia). That said, this game set the precedent for an entire genre of games and
REALLY introduced us to the Tex we know and love.
4. Overseer
--- I remember that before this game was released I sent Access an email asking them if this was just going to be an updated version of Mean Streets... and I had a hard time shaking that throughout. Graphically, this was much better than UAKM or PD, and Michael York was phenomenal, but the game had been rushed which showed in its brevity and inability to continue progressing forward with some of the concepts that had been introduced in PD (like multiple paths). The lack of the Chandler Ave. base left me a bit disoriented and all these years later makes me realize that while it's been 16 years since we've seen Tex, it's been even
LONGER for the likes of Louie, Rook, and Co.!
Mean Streets and Martian Memorandum aren't even on the same planet as the FMV games, but I will say this. My first introduction to Tex was as a teenager on a Commodore 128 in C64 mode playing Mean Streets. I spent hours jotting down notes and playing detective, channeling an inner passion, while searching through the locations that reminded me of playing Maniac Mansion. There was arcade fun in the shootout sequences and the speeder mode was challenging. It was a very ambitious project with some great gameplay memories that made the decision to buy the FMV games when they came out a no-brainer.