Lowest you can get in the middle stops "Rock and Roll" but we like about deck 6 middle.
for day to day cruising. So, middle or towards the rear. not toward the front, is the rule..A.
We always stick to middle or just forward of middle....we find that further back tends to have more engine noise....we did have a cabin right on the stern once and had terrible vibration when the ship was manoeuvering. we also try and choose a cabin with other cabins above and below rather than above the theatre or under the sun deck (when you hear the crew arranging the sunbeds at silly oclock in the morning!).
On OV1 in particular you should avoid cabins on deck 5 (or P deck) anything aft of P176/P179 as at this point there is a major bulkhead and from there onwards towards the stern is the engine room area. A simple walk down the corridor highlights a significant change in background noise levels past these cabins. In the past I have had both P165 and 167 and these were both quiet (despite the cinema being opposite which was well soundproofed). Above you there are cabins and below there is a selection of cabins, the medical centre and possibly some store rooms. Anywhere around there would be ok. Being low down also minimises roll. If you want to be higher up then, as already suggested, have a cabin where there are cabins above and below you.