I feel that basing achoice of study on public popularity is the wrong reason to study anything - oops! [&:]
Both these disciplines are huge fields of medicine that is usually only taken on by those that are passionate for the subject. I'm a supporter of them both, but I'm just pointing out that either are a huge commitment. By their very nature's they are the proverbial life time of ongoing study.
The number of UK practioners would give you a general guide to popularity and this you could get a rough estimatefrom the respective UK professional bodies.There are several for each.
In the Wirral,Cheshire & Merseyside areas at least it seems we have more enquiries for acupuncture. I am basing this the number of enquiries and treatments at ourholistic centre and a couple of other practices I work at, which both have acupuncturists.
Also, recently homeopathy has had a bit of a kicking from the anti alternative medicine doctors in the media, whereas acupuncture has had a couple of positive research studies published of late. There was a definite increase in inquiries for acupuncture after the BBC series on alternative medicine a few months back, although how the fickle public will feel in 3-4 years (expected study) is anyone's guess. That said I as sure as I can be that they'll both still be around and likely more popular than ever.
Hope that helps - Andrew.