When I said uglier, I rather meant to say awkward, but followed Gepard's line as he said the Su-57D was ugly. I fully agree with you and I also admire all aircraft. It is just that the MiG-25UB and Yak-38U appear like forcefully created. As if the designer always had only a single-seater in mind and never intended to make a trainer version, but was pushed by the government to develop one (which to my knowledge was actually the case sometimes). So, the single-seat nose section was chopped off and a two-seater one was forcefully stuck instead. For the lack of a better word in my vocabulary, the design of these aircraft does not look as natural to me as compared for example with the MiG-21U/US/UM and the MiG-23UB. The MiG-29UB with the pilots cabin pushed forward in place of the radar section for me is in the middle as it is not as awkward as the MiG-25UB and the Yak-38U, but also not as natural looking as the later MiG-29KUB and the MiG-35UB. The trainer versions of the SR-71 and U-2 are up there as well with that additional cabin stuck on top of the fuselage. So, there are awkward designs on both sides. Hope you get my point despite the obvious lack of proper vocabulary (should have read more books in English at high school).