I've been trying out Scrypt.cc for a couple of weeks now and have been impressed enough to recommend it in my signature. You dont get to choose where your KHS are mining, but their pool consistently achieves similar profitability to the top multipools.
No doubt you have seen
Suchmoon's profitability comparison thread - his figures correspond closely to my own for the options I have been trying. Also makes it clear that you need to take a reasonably long term view, weeks/months rather than days, because the markets can be so variable.
I'd also say it depends how much time you want to invest, since you're asking about cloud hashing I'll assume you don't want the hassle of maintaining your own mining hardware
Leaserig.net can be handy for short bursts of mining if you can get in ahead of the crowd - recently there was a big profitability spike with CINNI and WC coin launches that saw the average cost per MHS/day go from about
BTC0.006 to
BTC0.015 in a few hours. If you had hired a load of MHS for 24hrs at the start of that rush and sold all the coin you mined straight after then you'd have made a respectable profit, but those opportunities dont come along often - for day to day mining you'll struggle to make a profit at all.
I haven't tried Nicehash myself yet as it appeared to be a variation on the mining rig rental system, and I figure most miners will only rent their hashpower at rates which make them more return than mining on one of the big multipools, so the situation is the same as I just described with leaserigs.net.
Since you say you have plenty of BTC I guess you may be looking for a way to generate some income from them rather than having them sit in cold storage. Whatever you do, the higher the potential income the higher the risk is going to be too, but I suspect you know that or else you wouldnt still have plenty of btc
My suggestion would be to split your investment 50/50 initially - half to buy KHS at Scrypt.cc and the other half for Nicehash etc, then keep records for a few weeks and see what averages out best.