Area PD is good, you just have to research decent ranged weapons for it. Final Defense only gets you 1 shot and ONLY against missiles targeted at that specific ship. Area PD gives you multiple shots, depending on the speed of the missile and the range of your PD - and most importantly, it allows all the ships in the group to defend eachother. Capacitor recharge rate 6 (only costs 59,000 points all total, 60,000 if you're conventional start) lets you have 15cm weapons with 5s refire, so you can use them for PD with double the range. Then the same level of Meson focusing (costs another 59,000 points) would let you get 15cm mesons with a range of 180,000 km. Lasers would be double that, but I always prefer mesons since they ignore missile armor and are always a 1 hit kill on missiles. The 15cm guns are only size 4, so 33% increase in size over the size 3 but the double range makes them far more useful.
For instance, lets say you have 5 PD guns with a range of 180,000 on your ship. An enemy fleet sends a volley of missiles going 55,000 km/s (pretty fast at that tech level I believe). Final defense would mean only 5 of the PD guns would fire, getting in one shot each at 10,000 km right before the missiles hit. Lets make it tough and assume the missiles are at 185,000 range before they enter your weapon range, so they'll be entering with a 50km advantage. Area defense would mean that your guns would fire at 130,000, 75,000, and 20,000 - giving you 15 shots at the missiles. Move into a fleet situation and the advantage grows - say you have 2 ships. If the volley was targeted at ship #1, only he would use final defense and you still only get 5 shots. With area defense, both ships would fire as it approached - giving you 30 shots. If you have a reasonably fast ship you can sometimes even get in an extra shot by flying away from the missiles so that they close slower.
I still use the 10cm mesons on occasion for final defensive fire. For those you can make them cheap like this:
Max Range 15,000 km Rate of Fire: 5 seconds Focus Modifier: 1
Meson Cannon Size: 3 HS Meson Cannon HTK: 1
Power Requirement: 3 Power Recharge per 5 Secs: 3
Cost: 3 Crew: 30
Materials Required: 0.6x Duranium 0.6x Boronide 1.8x Corundium
Then just slap it on a turret and add a size 1 fire control set to 25% size/range and 4x size/tracking speed. It makes a good "CIWS" system using armor piercing mesons instead of gauss, which can be a lifesaver against armored missiles. Final defensive fire has its place, but don't neglect area defense.