I'm not sure if this has been talked about or not but I believe the strongest fusion character would be a Potarra fusion between Goku and Piccolo. And no I do not have a name. A fusion between them would be stronger than Gogeta and Vegito. Why? Because Piccolo's base power level is much higher than Goku's. Vegeta is kind of unecessary because Goku has more SSJ levels than he does and Vegeta's base power level is either equal to or a little less than Goku. Combining Piccolo's high base power level with access to Goku's SSJ transformations will make the fused character very strong.
During the Buu Saga, Vegeta became roughly equal to Goku's power when he became Majin Vegeta. Majin Vegeta died fighting Fat Buu, who was given a power level of 1,000,000,000. So, at most, SSJ2 Vegeta could only have a max power level of 1,000,000,000. I made it equal because Fat Buu's regeneration ability would have given him an edge even if they had equal power levels. So if SSJ2 Vegeta had a power level of 1,000,000,000 as a Super Saiyan his power level would be only 500,000,000 and his base power level could not be more than 10,000,000. Since Majin Vegeta and Goku were close to equal in strength, not counting SSJ3, then Goku's base power level couldn't have been more than 10,000,000.
Since Piccolo did not fight much during the Buu Saga it is harder to get a grasp on his strength. So, we go back to the Android saga before he fuses with Kami. He's strong enough to beat Dr. Gero who has been enhanced. I think Dr. Gero and the fat Android have to be at least on Freiza's level of strength: 120,000,000. Otherwise those androids would have been too easy for Vegeta and Goku, despite his heart disease. Given how fast Future Trunks beat Cyborg Freeza so easily and how Vegeta and Goku were stronger than him after three years makes it more likely that Androids 19 & 20 were at least on par with Freeza if not stronger. Since Piccolo was stronger than Dr. Gero his power level had to have been 120,000,000+. And then he fused with Kami enabling him to go toe-to-toe with Android 17 who had previously had knocked him out in two hits. Then he did some Hyperbolic Time chamber training to get even stronger. After that seven years had past and Piccolo is constantly training, probably not as hard as he usually does, so his power would have increased more. I think it is highly likely that Piccolo had a power level somewhere between 400,000,000 - 500,000,000. Think about it. During the Android Saga Vegeta, Goku, and maybe Future Trunks had to be at least 200,000,000+. That means the 17 & 18 had to be at least 300,000,000+ given how easily they thrashed Vegeta and Future Trunks. I think it is at least conceivable that Piccolo could have a power level in the 400,000,000 - 500,000,000 range.
Even if Piccolo only had a power level of 400 million if he Potarra earring fused with Goku, who has a base power of 10 million, and not including the unknown multipler that comes with the fusion . . . the fused being would have a base power level of 410 million. If he transforms into an SSJ his power level would be 20,500,000,000. As an SSJ2 it would be 41,000,000,000 and as an SSJ3 it would be at 164,000,000,000.
There you have it. The strongest fused character ever. Yes, I've made assumptions, but I think my estimations are fairly close.
Let me know.