What do you want?
Line 1 - Fighters
The Vampire, Venom and Hunters are the main dogfighter of that range for our tree. Good, though maybe a tad over BRed these days. The Hunters can be especially good, though the 30mm ADENs are tricky to use and the SRAAMs on the Hunter F6 can be unpredictable.
This line also leads onto the Phantom FGR2, a main stay high tier fighter for us, though best used for close range SARH missiles, and unfortunately Over Br’ed with its current loadout and eventually onto the Gripen C, our top tier fighter. One of the best dogfighters in game.
Line 2 - Interceptors
Lightning F6 is a very fast, hit and run aircraft, one of the few super-sonics of that BR range, but is a tad limited by the performance of the Red Tops and the tricky nature of the 30mm ADENs. But quite a fun aircraft nonetheless. Just dont try to dogfight.
This line leads onto the Tornado F3s. These are very potent BVR trucks and can be highly effective when used right, recent buffs have given them a new lease on life, though still in need of further refinements, mostly in the CMs
Line 3 - Naval
Scimitar is a quick and fairly potent naval fighter, though one I havent got a vast amount of experience in.
This line leads onto Sea Harrier FRS1e which can be very fun, though is in need of some notable buffs/bug fixes. Below that is the FG1, a carbon copy of the FGR2 except for some difference in the landing gear and the Sea Harrier FA2, which is a very good top tier AMRAAM slinger (when downtiered), but also in need of some notable buffs/bug fixes
Line 4 - Strike aircraft
Jaguar’s are decent strike aircraft, with good payload and overall performance, but ARB is a poor enviroment for them, excellent in ASB though. The Gr1A has the advantage of flares, the Gr1 has the advantage of a lower BR, but overall they are the same.
Also in that line is the Harrier Gr3, a good strike fighter, and can be effective in air to air combat, though that is not its main role. Like all Harriers, it can struggle to deal with IR missiles, but with proper throttle management this can be mitigated. Learning to use the vectored thrust is highly important in all harriers. At the bottom of this line current is the Harrier Gr7. One of the better CAS aircraft on our tree at the moment and a capable dogfighter when used right, It carries the Aim-9M which is both a blessing and curse, in that it is good, but forces the Harrier Gr7 perhaps higher than it should be placed. The Gr7 also has excellent CM count and MAWS
Line 5 - Bombers
The Canberras are very good bombers for the BR range and the Canberra Mk6 even has a gunpod, meaning it can fight back or hunt other bombers surprisingly well. An aircraft I dont have much experience in, but have heard it is truly a laugh to dogfight fighters and win in.
This line leads onto the Buccaneer S2s, both very powerful base bombers, with some of the largest bomb loads in game, though both can be vulnerable to attacks at their respective BRs, with no guns and limited 2x AAMs for self defence (if you choose to take any at all) they can be tricky aircraft to use in ARB like all bombers are. But excellent fun in ASB.
F-111C is an aircraft I have yet to research, but boast good top speed, good bomb load and a good defensive loadout. The Tornado Gr1 below that is a very capable base bomber, though perhaps a tad slow for the BR range, making it hard to reach bases within ARB, But is very well equipped to deal with incoming threats. Very fun in ASB, with the right team.
(Whilst it is only a rumour, the Tornado Gr4 may be coming in the next major update, and that could be a very very good strike aircraft and if its got its full IRL loadout, one of, if not maybe the best CAS aircraft in game)
Conclusion
So it really comes down to what you have enjoyed so far the most. If its dogfighting in a spitfire, probably aim for the Hunters, if its hack and slash tactics, then the Lightning, if its more multirole, defensive gameplay, the naval line and if its mud moving then either the Jagaur or Canberra.