Oh boy, opinions and complaining my two favourite things. (jk)
-Anyways for small ballistic mounts I'd say the light mortar; their projectiles are slow and somewhat inaccurate, kind of easy to dodge them which is a big disadvantage in frigate Vs frigate battle where they'll see the most use. The light assault gun has the same range but is more reliable in my opinion, sadly these are the only two high explosive weapons for small mounts.
-Small energy would be mining laser; the low damage makes it useless against most missiles, I'd rather spend the extra OP for a LRPD which in my opinion is the best energy PD along with the small burst laser or at the very least get a normal PD laser. A close second would've been the Tactical laser; seriously does that thing even work ? I've never seen it do anything remotely threatening to other ships, at least it makes for amazing pd if you have integrated point defence which is it's only saving grace.
-For small missiles it would be the single Atropos; Atropos missiles in general feel like a slight downgrade of harpoons, they deal a bit more damage but they sacrifice 1 ammo and most of their tracking, they often feel very unreliable.
-Medium ballistics, you guessed it, Thumper; not even IPDAI can save this considering it is more expensive than a Flak cannon, Arbalest canon and Heavy mortar all of which are useful in their own roles.
-Medium energy, I'm not too sure, the Ion pulser actually seems like an interesting choice for fast frigates since heavy blasters tend to be too much for them. I'd say the Gravitron beam; it sounds decent but in practice you need at least two for ot to work well against any ships with decent shields and flux; the Ion beam I feel does a much better job at suppressing and you only need 1 of them.
-Medium missiles, obviously the prox charge launcher, however a close second would be the Annihilator rocket pod; they just get shot down by PD so easily unless you can use them in large amounts and are extremely hard to aim if they are placed on a hardpoint, the Onslaught is the only ship I ever use them on and even then I wonder how Reapers or harpoons would do.
-Large ballistic, I'm not too sure either, all of the weapons fill their niche very well even the storm needler which is a close range brawling weapon, I guess the devastator due to it's flux cost but even then I have to admit that it can clean up an entire area of missiles.
-Large energy, Paladin PD; waaaay too flux hungry.
-Large missile, Squall; I know some people will say the Cyclone Reaper launcher is unreliable and an overpriced version of the Typhoon reaper launcher but I absolutely despise the Squall, bad tracking doesn't do anything against armour it's only role is to sloooooowly build up flux on shields (which is defeated by flickering your shields) and in general I find it to be a very boring weapon.