I'm currently using TI Spirocore Weichs. Very clear and growly, but I would prefer something a bit more muted.
I've tried 10 or 12 different sets of strings and have come back to spiros. Steve Azola updated the pickup and preamp on mine to the latest version - this made a big difference (do a search and you'll find a review). I start with the high and mid controls on the preamp all the way down and open them up so I get just enough growl without the metallic finger noise. With darker orchestral strings such as pirastro flexocore I found I wasn't able to get much growl at all although they did get a nice round thumpy tone. I feel I get that thump along with some growl with sprios by rolling off the highs and mids as needed.