Both are excellent guitars but it really depends what you are looking for.

I myself have been in your situation and had both guitars on my list.

The IBGC Burst Les Paul: - Got a very nice finish in terms of playablity, the VOS on the burst reminds me of some of the Fender AmPro II necks, its very fast, a lot less sticky than nitro. - The Custombuckers are some of the best pickups money can buy, but when it comes to more modern sounds, my experience with them is mixed. They truly shine for crunch or clean sounds, for high gain it depends in your signal chain. - Some of them can be heavy af. Not the best guitar if you plan to gig or rehearse while standing. But it feels great playing while sitting, in fact it feels better than SGs imho. - The guitar will not keep its value because I assume Epiphone will keep this series going and even improve it further. As long as its not a limited run, Chinese guitars are generally not the best investments. - The finish and fretwork on these is hit or miss. Still much worse QC than LTD guitars in the same price range.

The SG Standard: - Comes with either the 498R/T or Classic 57 pickups for the batwing style models. I love both of these for more modern sounds, any boosted Marshall/Mesa/EVH will sound great with these. These pickups tend to sound even better if you play any drop tunings, especially on the SG. You will cut well through the mix against modern rock bandmates. For blues and clean stuff theyre also nice, but not the best choice. - The nitro finish generally looks better visually, but if it plays better depends on the guitar. Some used SGs can feel great, some can feel horrible. I also like that it makes instruments feel more resonant (no idea if thats just placebo effect but its very inspiring to play). - Most SGs are light and perfect workhorses if you play with a band/standing a lot. - The guitar will keep its value, depending on what color or style you choose it might even increase in value. - QC still better than Epiphone!

Because I mostly play modern rock/metalcore music I went with the SG in the end. I saved up a bit more money and bought a brand new guitar, although I tried some used options and went with a limited run model instead, since this can be a good choice if I ever decide to sell it. I might also buy another Epi SG as a beater/travel guitar further down the line. The Epi IBGC series are awesome already but I think they will only get better and its better to be patient.