Assuming it was ever great to begin with of course, consensus is that Kaioken beats it by a mile. Which I don't think should be the case since in the series it's almost better in every way. The main argument I see against this is that making Super Saiyan objectively better would make Kaioken obsolete (also kinda like in the series...) but IMO that doesn't really hold up...
For starters Kaioken is a universal skill so untransformed nameks and majins can still get use out of it, and Kaioken would still be viable if SSJ is on cooldown anyway or at least useful for short bursts.
Going back to what I said earlier, SSJ, in the series, was pretty much a substantial power up that put the user at a completely different level from their base form and the go-to form for any sort of real combat. The IG Transformation just doesn't reflect that, and reduces it to a minor increase in stats that may or may not be useful, and overall just more trouble than it's actually worth.
And yes technically this thread HAS been done already, but now that SSJ is in I feel like it's about time we discuss what to do with it since it's basically blank slate.
Here's are some ideas that I've seen floating around that I think are worth Noting
SSJ SP: Maybe pour some 1 or 3 SP into SSJ after wishing for it, to gain some extra perks. Perhaps Mastery would include a more generous drain in EP, bigger boost in power overall(you know... kinda like the series?), maybe even a smaller cooldown
Make it more like the potion: Idk the exact numbers on the potion but here's a side by side comparison
So I don't how this translates in a practical sense, but It seems like the potion outclasses the transformation by a fair amount, so maybe this might be the way to go for the SSJ transformation after all
I also think that the SSJ transformation should affect DEX and FOC, since Earthlings tend to be DPS classes and crits are basically their bread and butter, but that could be a tad bit unbalanced so let's keep that one in the "maybe" pile of ideas
TL;DR: SSJ is pretty underwhelming compared to how it was in the series, and now that it's back in action I feel like now's a good a time as any to figure ways on how to put tot the "Super" back in SSJ