The Archon all by himself seems risky. He doesn't have the toys he'd need to threaten anything really.
By taking a Court of the Archon instead, you have better options.
- Keep it really cheap, with a single Lhamean, in which case its effectively just tax for your HQ slot and the venom. This same you 65 points, and you could argue the Lhamean is better in combat against some targets than even your Archon is.
- 3 Medusae in the venom will do wonders against Meq, and they'd be only 5 points more than your archon.
- Slyth are pretty tough, and fare well in close range. They're the same price as Medusae iirc.
You can mix up the comp too - for example, 3 Slyth, one Medusae and one Lhamean does a lot of things to an opponent. You have majority toughness 5, with FnP from the get-go, a fair bit of dakka, a cheap Lhamean to tank Challenges (and possibly kill the enemy character if you're lucky with her).
Don't splash out for the models unless you really want them - you can convert most of these units from regular Kabalite/Wych frames and a little greenstuff.
As for Incubi, the models are gorgeous, and the unit itself can be fantastic. It would be tough justifying them in games lower than about 1200 points, however. If you do wish to include them, a simple squad of 5 with a Klaivex is good at hunting down squads of well-armoured infantry. Just avoid assaulting through cover like the plague.