Logistically north-south is easier, but it means you are confronted with Raggedstone Hill right at the end of the walk. It's hardly Tryfan, but is a total pig! South to north you get the horrible hill over with first, and also end up at Malvern, which has caffs and the like 
If you're doing it both ways, this is, of course, all academic! BUT bear in mind this is 20 miles and 6000 feet of ascent.
There's a way off the hills to Colwall, which would make a walk of about 8 miles, Colwall is the next station on from Malvern in the direction of Hereford. There's also the possibility of circular walks back to Malvern, taking in St Anne's Well, which has a caff.
If anyone wanted to overnight, there's camping close to Chase End at the southern end of the hills and, although strictly a bit naughty, opportunities to wild camp in the woods around there too.