For a while I had 3 sigmas - the 10-20, 24-70 & 70-300 APO...but as you can see I have passed on from that time. But for a while those 3 were my main kit.
can I ask why the 10-20 when you have both crop and FF? I ask, because I'm facing the same decision right now. I have a 5Dii and 7D and the 10-22... Not sure if I want to swap it out for a 17-40 or not...
I would say that the ef-s 18-55mm IS, ef-s 55-250mm IS and 50mm 1.8 is awesome and affordable 3-lens kit. Probably the best bang for the buck. As a bonus it's extremely portable and light.
yep, maybe swap the 50 for a 10-20 or 10-22 if you're a wide person and your budget allows, but all three of those options are GREAT starter kits covering a LOT of bases.