It really is up to you which you like more. Important to get it right so no regrets later. These subs are still rather small if you look what people have in their dedicated spaces of similar size to yours so they definitely aren´t too much if you are afraid of that. You are in control how loud the sub plays and the recommendation is always get the best sub you can afford which fits to your requirements.
If it would be my money and use mostly movies then P12-PR for 480£ in satin black! I have chatted with few owners as i have given few options to them and they picked that PR model. They were blown away afterwards in a similar way like AVF`s Steve Withers.
The BK Electronic P12-300SB-PR delivers value and performance thanks to a combination of experience and direct retailing.
If you feel the basic sealed P12 is enough to you in satin black i urge you to call to Colosussxb cause the satin black goes usually 346£ + 10£ shipping as new grade-b. You would need to ask is there any of those available and if not then when coming. Also reviewed by AVF: