Leisure Select and Business Premier are basically the same seats and you can get a seat on your own with a laptop socket. Standard is slightly more crowded.
Standard seats are getting a bit ratty. Leisure Select has more families. Although Business Premier is theoretically just for business travellers, you also get families with more money than sense so it can be just as noisy.
If the client is willing to pay for Business Premier then great, otherwise it's no great loss as you're not generally hanging around long enough to take advantage of the business lounge.