I can't tell you what you like or what to buy, but if you decide to keep the SE, then a free-ish solution to your forwardness issue is the Felian3 port mod and goldilocks height adjustment (as I posted recently). The port mod will also increase punch. This could possibly benefit the Susvara as well, but that appears to have different pad clip design, so I'm not sure if the same mod will work for Susvara.
Edit: EQ will of course also help if you can find one that doesn't impact transparency.
The solution to SE's L-R panning issue is a good cross-feed, as I've previously posted.
The solution to Susvara's punch issue is a more powerful amp (in particular, ones that have high Instantaneous Current Delivery).
Personally, I'm biased against the Susvara because, as a downsizer, I don't like its amp constraints. And I don't like Fang's blatant, cynical, over-charging of this model (compared to the cost of parts). Yes, all high-end has high markups, but I feel Fang took it to new heights (lows?) with this model. But if neither of these points bother you, then most people would say that the Susvara is fundamentally the better sounding headphone and will scale the highest with better upstream components. The SE will also scale well with better upstream components - it doesn't need a powerful amp, but it will reward better quality everything upstream.