which sub/amp combo is better choice?

I would say stick with the L5.. especially if space is limited.  RMS wise.. 2 cvr's may have more power, but the L5 may be just as loud in the right enclosure and it's is a great SPL sub, which seems to be what youre going for.  Either way youre going to be beatin down the block and turning heads.  You should also think about the long run.. if youre on a low budget, going with more powerful system may not be the best idea. Approaching that wattage means it could be time for a new alternator/ battery, especially without using a capacitor and in an old car like that.  And if you blow your alternator you'll really be spendin some cash.  If you were in an SUV and werent tight on money.. id say why not to 2cvr's.. but in your given circumstances, it looks like the L5 would be your best choice.  And it's a great sub.. i have 2, with a hifonics titan amp that runs 1000 @1 ohm and 700 @2 ohms.  lucky for me i can choose whether i want to run 1 sub at the 700, or both at 1000.  With just one it is ridiculously loud and i wiz off everyone who lives on my street.  I am also in your position with space, in an 01 neon.  But maybe im playing favorites because i have that sub and have never heard a cvr.. who knows! Hopefully this helped a little.

The type of box youll be putting it in has a big influence on how each with sound. Personally, i am a fan of sealed boxes.. one of the few it seems.. i am like you and listen to all genres of music.. and i dont like the bass hitting late in the rock songs, which you usually get from a ported/vented.. while the sealed is more accurate.  But when listening to rap.. i sometime wish i did have a ported box.. to get that extra kick on the lower frequencies.  But my small car keeps me with the sealed box because they are smaller. and ive been very pleased with it.

Put the L5 in a ported/vented - youll get head turning bass.. put it in a sealed - youll geta little more SQ

Put the Cvr's in a ported/vented - ill bet it wont fit in your car.. put it in a sealed - and youll have yourself a nice overall system in my opinion.

The L5 in the ported and the CVRs in the sealed will be a comparable "loudness".. just choose to your prefrence i guess.  As for a cap.. its hard to tell. some people tell you to go one way and some tell you to go the other.. its usually just a cheap way out of the "big 3" upgrade.. but may cause you to need one anyway. so maybe someone else can shed some light in this forum for you and your situation.

Frequency range of human hearing is 20 hz to 20khz.. so you wouldnt even hear frequencies down into the 10 range.. and you wouldnt want your subs playing anything up to 500.. thats usually why there are subsonic filters and low pass filters on amps.  The subsonic adjust how low you want the hz to go, while low pass controls how high you want it. an example of this could be 15 hz - 250hz. thats all you would normally need or want your subwoofers producing.