kicker 12 solo x vs 15 solo baric

What are you intending this for? SPL, Street beat? Also what kind of power you talking about runnig?

Yes the solo x is a SPL sub. It sounds pretty harsh but it will putout very much volume with lots of power. L7s and L5s sound much better and in a sealed box are pretty good for SQ. L7s will get louder than than L5s and are also built better. If you want a street beat set up i would say L7s ported with good power. You would get good sound and very nice volume. With less power and money over the solo x. If you are wanting SPL i would go Solo x and put the power to them. For SQ i would still do L7 sealed because it is built better even though they sound almost exactly like the L5. 

Im running a Kicker  ZX1000.1 per L7  ported im my Navi. Like i said it come down to what you want. A more true SQ sound or more bass. Ported they still sound great. But its not  true SQ. A sealed box is going to give you more consistant output through the freq range with less output. A ported box is going to be louder but in a  more narrow range. It comes down to you and what you want over all from your system. Playing loud and true SQ are 2 totally different things. If you want good sound and a lot off bass go ported. If you are leaning towards a more true SQ system go sealed.