Although the harrier is not finished, I use it regularly for a wide span of missions.. I don't know if you got the F/A-18C, that is worth it as well. I use them both for A/G mission and had a lot of fun until now. Apart from that both are capable of engaging fighters especially the hornet since it's focused to be a multi-role aircraft. I don't have the Viggen so I cannot comment about it but from what I read, the viggen is not the CAS type.. it's more of the hit and run type. If I'm wrong correct me !