Hi all new guy here and already need some advice. I have had my T3i for about 4 or 5 years now and i would like to upgrade to a better camera.I am looking for better quality images and the ability to do more low light work. The lenses i currently have for it are the canon kit lens,EFS 18-135mm 5-5.6 IS, The el cheapo EF 50mm 1.8 ll, EF 75-300mm 4-5.6 lll and the newest one i just bought, Sigma 17-50mm 2.8 EX DC OS HSM I would really like to bite the bullet and go FF and i could possibly swing it by buying used but i am afraid it would be awhile before i could buy a couple decent lenses as they are SO expensive. Could anyone please lead in a direction,with FF or ASP-C? I have been pricing the Canon 6D(not Mll) as that is where my budget is.OR are there any advantages to staying with the crop sensor and just upgrading the body? With APS-C, i was looking at the Canon EOS 80D which is about the same price as the 6D.Of course there is the advantage to crop as i already have some lenses unless the lenses are crap.I have mainly been using the newer Sigma for my general all around photos. Like i said,i really would like to do more low light photography,night skies and just general shooting,maybe some portraits.Just a little bit of everything. Thanks!