The reason solar isn't seen much is the fact the subclass relies on it's aspects without the aspects the entire subclass is basically dead one of them is almost useless in pvp without some major build such as lowering an enemies health down to get a kill with ashen (You need to do this twice before you can get a one shot grenade generally making it more of a 6v6 build plus one miss is gameover for the build). Void basically relies on overshield and bubble spam both are very powerful in pvp but without it I'd argue it's probably at the bottom. Arc right now relies on one shot melee and juggernaut to be broken so yet again once those are gone it's another subclass nobody will use. Stasis on the other hand is actually balanced only one thing is broken and it's how many stasis crystals you can spam other than that it's all good but no op. I think people avoid Stasis because it isn't just press button become op but requires a build.