You might give some thought to what you want out of AX combat. The ships are pretty dedicated builds and it takes a fair amount of effort to put one together. In no particular order: some things to consider.
Access to Guardian Tech and Engineering makes a BIG difference. I consider Gauss Cannons and Guardian Module Reinforcement mandatory. As long as you're going to make the trip, its not that much additional time to get the rest of the guardian stuff.
If you don't already have all the Engineers unlocked, the Guardian Power Plant, Distributor and HRPs are roughly equivalent to G4. The impact on going from no engineering to G4 is huge, but the jump from G4 to G5 is bigger than it may seem because while the incremental bonuses are small, the effect on your damage output and survivability is multiplicative. (e.g. a bigger PD means less heat when firing and so more damage during attack runs which means fewer attack runs leading to less damage taken...)
Synthing ammo for Guardian weapons is expensive, and the Guardian materials needed will generally send you back to guardian sites to get them. For this reason, I don't synth guardian ammo. I find the synthing mechanic annoying and generally avoid it across the board. Reluctance to Synth means certain styles of AX combat aren't available.
AX combat is largely about learning the behavior of Thargoids. The fights can be daunting at first. In Horizon 3.8, Interceptors have forgotten how to use their caustic missiles and only use their Shutdown Field Neutralizer on entering an instance. Sites like Bug Killer (any thargoid location withing 8km of a planet surface) prevent Interceptors from using their swarms. If you want a stepped difficulty introduction to Thargoid Combat:
Start with 3.8 at Bug Killer
Then 3.8 in a threat 5 Non-Human Signal Source
Then 4.0 at Bug Killer
Then 4.0 at a threat 5 Non-Human Signal Source.
Threat 5s give Cyclopes (or possibly scouts) You can actually check whether or not a NHSS has scouts or interceptors using the
FSS and there's another trick regarding the frequency setting (I believe the left half of the zone that picks up NHSS's indicates scouts while the right half indicates interceptors, but I might have reversed that).
The difficulty jump from Cyclopes to Basilisks is a big one. Especially if you're not going shieldless/cold orbiting.
I like piloting a big ship, so for me a heavily Shielded Cutter is perfect. If you prefer more of a dog-fighting experience you're going to want something like a Krait or Chieftan, and while you might start with a shielded or hybrid build, you're going to end up with a shield-less Cold-orbiting build if you want to get beyond Basilisks.
