A visitor visa on her own (which she would have to do if she hasn't met you) is least likely to be successful (and a spouse visa is most likely to be successful). If you want your relationship to go anywhere you need to go to see first.
Though I can understand your concerns, and what you I guess you need to consider is can you sponsor her for a settlement visa? To sponsor her for a settlement visa you need accommodation (which you have) and enough spare money each month out of your existing income.