Spouse/unmarried partners this week became more difficult with the introduction of new rules. It depends rather heavily on you as the British citizen (and therefore sponsor). The rules now require that you've been earning at least £18600 per year for at least 12 months, and also that you have a confirmed job offer waiting for you in the UK that meets this same level. If you have an exhorbitant amount of savings between you, you can use that instead, but otherwise it's suddenly become that much tougher. However, if you meet the requirement, this is probably the easiest route, depending on your circumstances.

You say your partner has a job available to him already in the UK - does he have a visa already or is his employer providing one? If so, then that could be your easier option. Another thing to check: are either of his grandparents British? if so, an ancestry visa would be worth looking at.

EDITED TO ADD: Too late! Slow server and me a slow typer - same answers as above