Key words: novice & hobby
While I like using my 100/2.8 for macro, I don't use it for that at all. Macro is specialized work and you would have to have a keen interest to get the 1:1 that the 100 offers.
Depending on the amount that they have to spend in descending order would be the MP-E 65mm, 100mmL, 100mm, other 90/100 macro lenses and then finally any of the EF-S lenses that have the short focus distances.
If it's flowers and objects up close I feel the EF-S lenses can cope but if the details are the interest then a dedicated macro lens is in order.
The Canon 100 2.8 I have is a very sharp lens. I'll use it as a portrait and landscape lens. I just wish it had IS, photography in a museum is hard without it.
2000 740i-Annalisa and 2008 335i-Weebl. Weebl may wobble but has DTC