I do RAW conversion using Capture 1 v6 (I've not upgraded). Once of these days I might try LightRoom, but no more than I shoot right now it's not worth it. I have RAW Therapee on my Linux laptop, but I've so far been unable to calibrate the screen so there's no reason to work there.

I usually use a very gentle Unsharp Mask, applied more than once, and usually end up undoing the last pass that made it look crunchy. Typically the results are better than one 'larger' pass. Also, decomposing the image into channels, sharpening the value (B&W) channel only then recombining sometimes works better. Also, always... always! sharpen at 100% view. If you're not pixel-peeping during sharpening, you'll never know how it looks.

I've used GIMP plenty over the years, but also used PSP 10. Neither are Photoshop, but nor are they as expensive, particularly with Adobe's latest shenanigans (Creative Cloud). In a lot a ways I like GIMP better than PSP, but its Unsharp Mask is SLLLLOOOOWWWW. If the GIMP developers will ever add support beyond 8 bit color, adjustment layers, etc., I'll probably end up dropping PSP. PSP was good when Jasc had it, but once Corel got involved it really dumbed down.