G19 is probably the best value around on a concealable handgun that packs a very good magazine capacity. I think ruger has made some steps forward with the SR series, but it is not a proven commodity like Glock is. I would not really call a G19 "compact" anymore, with all the small sizes available out there. That said- it is a very concealable commitment to having an effective firearm.
You'll have a lot more holster choices for the G19. Every decent holster made has a G19 offering. The holster is the most important part of effectively concealing- the right holster can conceal a desert eagle fairly well. You are looking for 1) a good gun belt and 2) a quality IWB holster that has two belt-mounting points for stability- crossbreed, comptac, desantis, and others make decent holsters for this. With that setup you will be ready to roll with a G19.
Sights, parts, mags, and everything else are going to be easier to get for the Glock. Unless you find an exceptionally compelling reason to get the SR9-if it is a close decision- go with the G19. You won't find yourself constantly wondering if you should have bought the other model. And if there is an exceptionally compelling reason to get the SR9c, why are you even asking?