I don't know where you will find the stats, but the prevailing wind is SW and the majority of the Gulf stream current flows clockwise around the UK, so clockwise is the way that I would go.
I guess it depends a bit on where you are starting from. If like me you were to start from The Solent then I'd go East to get the boring bits out of the way first and end on a run from The Scillies, through the west country and home. If I were to start from say Whitby, I'd go West for the same kind of reasons.
This is something I'm planning to do next year and my thoughts are anti-clockwise starting from the Solent. I ditto the response above, get the dull bits done first.
There was some discussion about this a while ago. IIRC, the general consensus was that clockwise was the easier way because the prevailing winds are SW ish. We get more days with the wind from S to W than all the other directions put together.
This means a beat up the channel, yes, but a reach or run up the west coast and across the top. Coming down the east coast, you might be close to the wind, but are unlikely to be tacking. Going the other way, you get a good reach up the east coast, then a beat across the top and down the west coast.
Are you planning on going over the top or through the Cally Canal? If the former, have a quick read of the Orkney and Northern Scotland pilots before you go. Either way is possible, but more caution is required Westbound, and hence suitable conditions are less common.
You wouldn't want to waste a wet and windy week of westerlies waiting in Wick. /forums/images/graemlins/laugh.gif
Going anti clockwise you will get only four and a bit hours of fair tide out of twelve going up the East coast, so I would go the other way. Wind astern and some decent Atlantic rollers to push you North, a fair tide and sheltered(ish) seas for a beat South. All things being as expected of course but the wind has been in the North for what seems an eternity at the moment so it's a good job you didn't do it this year.
Thanks for all the contributions. Clockwise seems favorite for wind and tide (Hythe start/finish). The plan is to cover two seasons and overwinter in Stromness. I've tried east about once and got as far as Southwold - nasty NW seemed then to be going on for ever.