I have more than one favorite Larry game, so I'll list them all and explain why I love them:
Leisure Suit Larry in the Land of the Lounge Lizards EGA
When I rediscovered old Sierra games like The Black Cauldron and King's Quest, and I rediscovered this game, and I really loved its dirty take on the graphical style of Sierra's fantasy games. I like the EGA colors (they remind me of another EGA favorite of mine, Duke Nukem 1), I like the backgrounds, I like how the women (especially Eve) are done, I like the freeroaming structure of the game, and I like how much interactivity Al Lowe put into this game. What's great about it is that its text-command parser interface still surprises me to this day with responses I didn't notice before.
Lesiure Suit Larry 6 Shape Up or Slip Out
I like the women designs, the voice-acting, the very early-mid 90s feel to it, the humor, and the eroticism. I especially got a thing for Shamara, the generous New Age lover.
Leisure Suit Larry 7 Love for Sail!
The only animated adventure game I got to properly play was Torin's Passage. I knew I was going to enjoy this game, because It combines some of the best elements of Torin's Passage with the best elements of Larry 1 and 6. It also is a great expansion upon the ship level from Larry 2, and I can see even a little bit of that game's influence on Larry 7 (but overall, far better done). As with Larry 1, I like the immersion in this game, I like the plethora of responses you get, I like the interface, the explicit dirty humor, and I like its nonlinear structure. Of course, I like the exaggerated-bodied hot women of the game, especially the ones who tend to chew Larry up and spit him out. Admittedly, there are aspects of Torin's Passage that I wish was in Larry 7, and there are aspects of Larry 7 that I wish were in Torin's Passage (or even King's Quest 7, which started the Disney-like cartoon style for the other two games). Though I love Leisure Suit Larry Reloaded, I even wish that game had the same kind of animation that Larry 7 had. I want to see Larry 7 used as a template for other Larry remakes, if they ever happened in my lifetime.
Leisure Suit Larry 3
It's a huge improvement on Larry 2, and I like the SCI graphics of that game. I like the women, the humor, and it was the one game where I felt some sympathy for Larry. When Larry thought that Patti was thinking of another man after they slept together, I felt bad for him when he said that he was tired of being a loser (the misunderstanding is contrived, but considering the abuse Larry receives later in the game, I pity him most during this scene). I don't like having to do the river log arcade game just to get a complete score, and some of the jokes were lame, but it was definitely one of the best SCI Sierra games I've played.
Leisure Suit Larry Reloaded
The way the game was remade is close to how I want a Larry game to be done in this era. More could've been done with it, but it's still an admirable start (even though we may never see any more remakes for Al Lowe anytime soon).