The first Fallout I tried was this one (FO:Tactics). I liked it a lot and spent an incredible amount of time going through the missions and enjoying the combat/story/atmosphere. It is incredible how well this game goes with beer and peanuts. And loads of free time that that will eat with no problem.
After liking this game so much I decided to try Fallout 1&2. I have to say I didn't like them so much. They had a different flavor (that I have to say was not bad at all), but... Tactics was the first love. I know die-hard fans of FO1&2 will probably try to flame me for this, but it won't work with me. So yeah, FO1&2 can not be compared with Tactics. They are different things. What Tactics is, it is an excellent squad based tactic action RPG. Boy... too much beer. If you like to manage you assault squad into the best firing positions and give them the appropriate weapon, if you like to spent long minutes deciding which skill is best suited for the next level-up of each team member or if you simply like the loot :D then you can not go wrong with this. It is definitely a top of the line game. I gave it maximum rating because it deserves it. No but's and no maybe's. Get it, play it and then re-play it ('cause it has also great re-play value).
P.S. Did I mention you need beer for this one?
P.P.S. And peanuts.