For the lazy 
7" midbasses.
King of the 7" midbasses with respect to clean low frequency output is clearly the Extremis. Best performance at 50hz and up period, and by quite a large margin. You pay for it with a soft poly cone and crap efficiency though, Imo.
XXX... not a bad driver, but nothing really great either. Good bass output, but not as clean as the Extremis. Low inductance. Soft poly cone. Average distortion performance, but high bass output capable.
Seas G18RNX/P. Great budget driver. Distortion is slightly better than average. Good efficiency. High output bass capable. Smooth top end response.
Seas W18 Excel E001. Good driver. Crappy suspension with a huge forward bias. Lower than expected efficiency. Great low end frequency response for IB use in doors. You don't need a notch filter, or even a lowpass for this driver when used in doors. You won't hear a difference.
Seas W18NX. Kills the W18 Excel. Think of this as a G18RNX/P, with a bit more efficiency and bass output, but much lower distortion and a higher price tag. LE curve one of the best in it's class. BL curve near perfect.
Midranges:
Peerless exclusive 4". Pretty much best performer of the pack. It will play the lowest, with the highest output and cleanest performance. Rough upper end frequency response, not as nice as others.
A crapload of Tangband and Audax stuff. Varies from better than average to downright nasty. Good performers generally for the money.
CSS FR125S Nice mid. Way better top end extension and smooth response than the Peerless. Bass performance is better, but strangely not the lower midrange. It still beats all the others though.
Vifa trius. For those that want a midrange that has the top end response of a tweeter. Lower end performance has high distortion, but still good for such a small driver. Is it audible? I dunno, but it's significantly worse than the 4.5" drivers and Imo does sound "strained" if attempting to reach 200hz at 96db spl @1m.
7" midbasses.
King of the 7" midbasses with respect to clean low frequency output is clearly the Extremis. Best performance at 50hz and up period, and by quite a large margin. You pay for it with a soft poly cone and crap efficiency though, Imo.
XXX... not a bad driver, but nothing really great either. Good bass output, but not as clean as the Extremis. Low inductance. Soft poly cone. Average distortion performance, but high bass output capable.
Seas G18RNX/P. Great budget driver. Distortion is slightly better than average. Good efficiency. High output bass capable. Smooth top end response.
Seas W18 Excel E001. Good driver. Crappy suspension with a huge forward bias. Lower than expected efficiency. Great low end frequency response for IB use in doors. You don't need a notch filter, or even a lowpass for this driver when used in doors. You won't hear a difference.
Seas W18NX. Kills the W18 Excel. Think of this as a G18RNX/P, with a bit more efficiency and bass output, but much lower distortion and a higher price tag. LE curve one of the best in it's class. BL curve near perfect.
Midranges:
Peerless exclusive 4". Pretty much best performer of the pack. It will play the lowest, with the highest output and cleanest performance. Rough upper end frequency response, not as nice as others.
A crapload of Tangband and Audax stuff. Varies from better than average to downright nasty. Good performers generally for the money.
CSS FR125S Nice mid. Way better top end extension and smooth response than the Peerless. Bass performance is better, but strangely not the lower midrange. It still beats all the others though.
Vifa trius. For those that want a midrange that has the top end response of a tweeter. Lower end performance has high distortion, but still good for such a small driver. Is it audible? I dunno, but it's significantly worse than the 4.5" drivers and Imo does sound "strained" if attempting to reach 200hz at 96db spl @1m.