ah gee that ones hard, but I like Egon/any of the guys, basically, though he's got a very strong relationship with Peter, especially show-wise. Peter is a real source of stimulus for him and they have a lot of little in jokes and rub on each other's nerves. They've known each other since college and Peter apparently did a lot of copying of his work
but he wouldn't let him if he didn't like Peter a lot and think he was smart enough to be worth it in the end, since Peter had to write his own thesis and get approved for a doctorate after all.
I think they're a good ship cause Peter definitely knows how to make Egon laugh and smile consistently which is hard but I don't think they'd grow old together
I think they might be a tad unstable for that, at least Peter. But hey, who knows if Peter matures some ans finally settles down after realizing Egon is the blonde bombshell he deserves