So, scatter laser is a good secondary weapon for the Falcon. That's probably a good idea. I often use my farseer to GUIDE the falcons.
So, if I have 3 falcons and 3 waveserpents, where else should I look for more Anti-vehicle weapons? I also have several vypers with scatter lasers, they are probably not worth upgrading to Bright Lances.
alot of that depends on your playing style. there are lots of options-stick a squad of those elite guys with the entire squad equiped with assault metla weapons (can't remember thier name) in the back of a serpent, jet it out unload and shoot. if your serpents BL doesn't do the job the squad full of meltas will or they can choose a different target than the serpent.
war walkers also make good fire support platforms with scatter lasers, star cannons and bright lances.as optional weapons to do either anti-troop or tank work depending on how you equip them. they may not survive as well as a skimmer moving "fast" though.
vipers are like land speeders but worse with less firepower and being open topped, i personally would steer clear of them.
i don't remember if it is in the new dex, but i do recal that squad of jet bikes you can take where all of them have a bright lance.
think about the balance of your force so that it fits your playing style and has both vehicle and troop killing power.
the one weakness of my tau list is it is heavy on troop killing and light on anti-vehicle so i switched my crisis suited commander around to be a kamikaze tank killer to add some more AT to my standard list.
when i go over 2K i can put in a second HQ and equip each with a retinue so my AT work is pretty much dealt with.