If you have a proper garage and a bit of courage you can have brilliant sounding system in around around £1300.
I fully understand you don't want to do it yourself but if you hire a guy to do it all for you. Atleast you can project manage and choose and pick the right part.
IMO none of above options were looking good to me. They will achieve good result though but you can get similar good result by just installing tweeters.
X5 40d M Sports - Fully loaded, 7 seats.
Sold 535d LCI, Xenon Adaptive Headlights, ACC 2 (Stop and Go), LDW/TLC
Retrofits M5 heated/lumbar/memory and active backrest adjustment seats, rear heated and folding g seats, SAT Shifter, paddles (SA2TB), HUD, Rear blinds, Electric steering column, SA430 Folding and EC Mirrors, High Beam Assist, CIC, COMBOX Telematics.