I've shot with the Sigma 105mm, and I own:
Tamron 90mm
Sigma EX 50mm
Sigma 50mm (MF)
All four have delivered some great shots for me, and people have responded favorably to what I post (500px, PF, etc.) despite my skill level, so a true macro lens in your hands would yield some smoking results. The Tamron 90 was my workhorse early on, but I scored a deal on the Sigma EX 50, and it's ease of handling has moved it to the front. Pretty much everything I do is hand-held at this point, so a person with more skill/patience/lighting knowledge would do really well with any of the lenses I own. I always see you post flowers, so a decent 50mm might be a good bet. Both of my 50's are nearly half the size of the Tamron, so if you have shaky hands, the shorter FL could be a good help if you were to shoot hand-held. The only caveat would be working with a flash on that shorter FL (sometimes introduces shadows into the mix).
There is a chance that Santa might drop a Sigma 70mm or Pentax 35mm Limited into my kit (I inadvertently saw a text convo between my wife and my best friend about both lenses
). If that does indeed happen, and you are still looking, I would probably be looking to sell at least one of the macros from my current lineup (I scored both 50's from sellers that didn't know what they had, and would be more than willing to pass those same savings onto the next person), or you can just call it a day, and pick up a nice Pentax M 100mm f/4 for $100ish -- and get back to shooting
https://500px.com/spockasmick